Video coding method, video decoding method, video coding apparatus and video decoding apparatus

ABSTRACT

A moving picture coding method includes: making a determination as to whether or not to code all blocks in a current picture in the skip mode; setting, based on a result of the determination, a first flag indicating whether or not a temporally neighboring block is to be referenced, a value of a parameter for determining a total number of merging candidates, and a second flag for each block included in the current picture, the second flag indicating whether or not the block is to be coded in the skip mode; calculating, as a merging candidate, a neighboring block usable for merging; and coding an index which indicates a merging candidate to be used for coding of the current block and attaching the coded index to a bitstream.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation of application Ser. No. 15/252,971, filed Aug.31, 2016, which is a continuation of application Ser. No. 13/875,481,filed May 2, 2013, which claims the benefit of U.S. Provisional PatentApplication No. 61/645,812 filed on May 11, 2012. The entire disclosuresof the above-identified applications, including the specifications,drawings and claims are incorporated herein by reference in theirentirety.

TECHNICAL FIELD

The present disclosure relates to a moving picture coding method and amoving picture decoding method.

BACKGROUND ART

Generally, in coding processing of a moving picture, the amount ofinformation is reduced by compression for which temporal redundancy andspatial redundancy in the moving picture is utilized. Generally, amethod in which spatial redundancy is utilized is performed by transforminto frequency domain, and a method of compression for which temporalredundancy is utilized is performed by coding using prediction betweenpictures (this prediction is hereinafter referred to as interprediction). In the inter prediction coding, a current picture is codedusing a coded picture preceding or following the current picture indisplay order as a reference picture. Next, a motion vector is derivedby estimating a motion of the current picture with respect to thereference picture. Then, the difference between picture data of thecurrent picture and prediction picture data obtained by motioncompensation based on the derived motion vector is calculated to removetemporal redundancy. In the motion estimation, difference values from acurrent block in the current picture are calculated for blocks in thereference picture, and a block having the smallest difference value inthe reference picture is used as a reference block. Then, a motionvector is derived using the current block and the reference block. Thereis a moving picture coding scheme called H.264 which has already beenstandardized (see Non Patent Literature 1).

CITATION LIST Non Patent Literature

-   [Non Patent Literature 1] ITU-T Recommendation H.264 “Advanced video    coding for generic audiovisual services”, March 2010

SUMMARY Technical Problem

In recent years, broadcasting and distribution of content at a highresolution of 4 K×2 K have been being planned, requiring codingefficiency higher than that of such a moving picture coding schemealready standardized.

In view of this, non-restrictive and exemplary embodiments are describedherein to provide a moving picture coding method and a moving picturedecoding method by which coding is performed with increased codingefficiency.

Solution to Problem

A moving picture coding apparatus according to an aspect of the presentdisclosure is a method of merging a prediction direction, a motionvector, and a reference picture index of at least one merging candidateto code a current block, and includes: making a determination as towhether or not to code all blocks in a current picture in the skip mode;setting, based on a result of the determination, a first flag indicatingwhether or not a temporally neighboring block which is included in apicture different from the current picture and temporally neighbors thecurrent block is to be referenced; setting, based on the result of thedetermination, a value of a parameter for determining a total number ofmerging candidates; setting, based on the result of the determination, asecond flag for each block included in the current picture, the secondflag indicating whether or not the block is to be coded in the skipmode; determining, based on the first flag and the total number of themerging candidates, the at least one merging candidate from among one ormore candidates including a neighboring block which is either a blockspatially neighboring the current block in a picture including thecurrent block or a temporally neighboring block included in the picturedifferent from the current picture, the determined at least one mergingcandidate being at least one candidate usable for the merging; selectinga merging candidate to be used for coding of the current block fromamong the determined at least one merging candidate; and coding an indexwhich indicates the selected merging candidate and attaching the codedindex to a bitstream, according to the total number of the mergingcandidates.

The general or specific aspect can be implemented as a system, a method,an integrated circuit, a computer program, a computer-readable recordingmedium such as a CD-ROM, or as any combination of a system, a method, anintegrated circuit, a computer program, and a computer-readablerecording medium.

Additional benefits and advantages of the disclosed embodiments will beapparent from the Specification and Drawings. The benefits and/oradvantages may be individually obtained from the various embodiments andfeatures disclosed in the Specification and Drawings, which need not allbe provided in order to obtain one or more of such benefits and/oradvantages.

Advantageous Effects

With the moving picture coding method and the moving decoding methodaccording to an aspect of the present disclosure, coding of a movingpicture can be performed with increased coding efficiency.

BRIEF DESCRIPTION OF DRAWINGS

These and other objects, advantages and features of the disclosure willbecome apparent from the following description thereof taken inconjunction with the accompanying drawings that illustrate a specificembodiment of the present disclosure.

FIG. 1 is a diagram for illustrating exemplary reference picture listsfor a B-picture.

FIG. 2 is a diagram for illustrating an inter prediction coding methodperformed in a temporal motion vector prediction mode.

FIG. 3 shows exemplary motion vectors and reference picture indices of aneighboring block for use in merge mode.

FIG. 4 shows an exemplary merging block candidate list.

FIG. 5 shows a relationship between a merging block candidate list sizeand bit sequences assigned to merging block candidate indices.

FIG. 6 is a block diagram showing an exemplary configuration of a movingpicture coding apparatus in which a moving picture coding methodaccording to Embodiment 1 is used.

FIG. 7 is a flowchart showing a moving picture coding method performedby the moving picture coding apparatus according to Embodiment 1.

FIG. 8 is a flowchart showing details of processing in Step S100 in FIG.7.

FIG. 9 shows an exemplary merging block candidate list according toEmbodiment 1.

FIG. 10 is a flowchart showing details of processing in Step S105 inFIG. 7.

FIG. 11 shows a motion vector of each block for a skip mode when thepicture skip flag has a value of 1 according to Embodiment 1.

FIG. 12 is a block diagram showing an exemplary configuration of amoving picture decoding apparatus in which a moving picture decodingmethod according to Embodiment 2 is used.

FIG. 13 is a flowchart showing a moving picture decoding methodperformed by the moving picture decoding apparatus according toEmbodiment 2.

FIG. 14 shows exemplary syntax according to Embodiment 2.

FIG. 15 is a block diagram showing an exemplary configuration of amoving picture coding apparatus in which a moving picture coding methodaccording to Embodiment 3 is used.

FIG. 16 is a flowchart showing a moving picture coding method performedby the moving picture coding apparatus according to Embodiment 3.

FIG. 17 is a block diagram showing an exemplary configuration of amoving picture decoding apparatus in which a moving picture decodingmethod according to Embodiment 4 is used.

FIG. 18 is a flowchart showing a moving picture decoding methodperformed by the moving picture decoding apparatus according toEmbodiment 4.

FIG. 19 shows exemplary syntax according to Embodiment 4.

FIG. 20 shows an overall configuration of a content providing system forimplementing content distribution services.

FIG. 21 shows an overall configuration of a digital broadcasting system.

FIG. 22 shows a block diagram illustrating an example of a configurationof a television.

FIG. 23 shows a block diagram illustrating an example of a configurationof an information reproducing/recording unit that reads and writesinformation from and on a recording medium that is an optical disk.

FIG. 24 shows an example of a configuration of a recording medium thatis an optical disk.

FIG. 25A shows an example of a cellular phone.

FIG. 25B is a block diagram showing an example of a configuration of acellular phone.

FIG. 26 illustrates a structure of multiplexed data.

FIG. 27 schematically shows how each stream is multiplexed inmultiplexed data.

FIG. 28 shows how a video stream is stored in a stream of PES packets inmore detail.

FIG. 29 shows a structure of TS packets and source packets in themultiplexed data.

FIG. 30 shows a data structure of a PMT.

FIG. 31 shows an internal structure of multiplexed data information.

FIG. 32 shows an internal structure of stream attribute information.

FIG. 33 shows steps for identifying video data.

FIG. 34 shows an example of a configuration of an integrated circuit forimplementing the moving picture coding method and the moving picturedecoding method according to each of embodiments.

FIG. 35 shows a configuration for switching between driving frequencies.

FIG. 36 shows steps for identifying video data and switching betweendriving frequencies.

FIG. 37 shows an example of a look-up table in which video datastandards are associated with driving frequencies.

FIG. 38A is a diagram showing an example of a configuration for sharinga module of a signal processing unit.

FIG. 38B is a diagram showing another example of a configuration forsharing a module of the signal processing unit.

DESCRIPTION OF EMBODIMENTS (Underlying Knowledge Forming Basis of thePresent Disclosure)

In a moving picture coding scheme referred to as H.264, which is alreadystandardized, three picture types of I-picture, P-picture, and B-pictureare used for reduction of the amount of information by compression. TheI-picture is not coded by inter prediction coding, that is, is coded byprediction within the picture (this way of prediction is hereinafterreferred to as intra prediction). The P-picture is coded using interprediction with reference to one previously coded picture preceding orfollowing the current picture in display order. The B-picture is codedusing inter prediction with reference to two previously coded picturespreceding and following the current picture in display order.

In coding using inter prediction, a reference picture list indicatingreference pictures is generated. In the reference picture list,reference picture indices are assigned to coded reference pictures to bereferenced in inter prediction. For example, two reference picture lists(L0 and L1) are held for a B-picture because it can be coded withreference to two pictures.

FIG. 1 is a diagram for illustrating exemplary reference picture listsfor a B-picture. A reference picture list 0 (L0) in FIG. 1 is anexemplary reference picture list for a prediction direction of 0 inbi-prediction. In the reference picture list 0, a reference pictureindex 0 having a value of 0 is assigned to a reference picture 0 with adisplay order number 2, a reference picture index 0 having a value of 1to a reference picture 1 with a display order number 1, and a referencepicture index 0 having a value of 2 to a reference picture 2 with adisplay order number 0. In other words, a reference picture temporallycloser to the current picture in display order is assigned with areference picture index having a smaller value. On the other hand, areference picture list 1 (L1) in FIG. 1 is an exemplary referencepicture list for a prediction direction of 1 in bi-prediction. In thereference picture list 1, a reference picture index 1 having a value of0 is assigned to a reference picture 1 with a display order number 1, areference picture index 1 having a value of 1 to a reference picture 0with a display order number 2, and a reference picture index 2 having avalue of 2 to a reference picture 2 with a display order number 0. Inthis manner, a reference picture may be assigned with reference pictureindices having different values between prediction directions (thereference pictures 0 and 1 in FIG. 1) and may be assigned with referencepicture indices having the same value for both directions (the referencepicture 2 in FIG. 1).

In the moving picture coding method referred to as H.264, there is amotion vector estimation mode available as a coding mode for interprediction of blocks in a B-picture. In coding in the motion vectorestimation mode, a difference value between data of a prediction pictureand picture data of a current block and a motion vector used forgenerating the prediction picture data are coded. In the motion vectorestimation mode, bi-prediction and uni-prediction are selectivelyperformed. In the bi-prediction, a prediction picture is generated withreference to two previously coded pictures preceding and following acurrent picture. In the uni-prediction, a prediction picture isgenerated with reference to one previously coded picture preceding orfollowing a current picture.

Furthermore, in the moving picture coding method referred to as H.264, acoding mode referred to as a temporal motion vector prediction mode canbe selected for derivation of a motion vector in coding of a B-picture.

FIG. 2 is a diagram for illustrating an inter prediction coding methodperformed in the temporal motion vector prediction mode. FIG. 2illustrates motion vectors in the temporal motion vector prediction modein the case where a block a in a picture B2 is coded in the temporalmotion vector prediction mode. In this case, a motion vector vb is usedwhich has already been used for coding of a block b in a picture P3. Thepicture P3 is a reference picture following the picture B2. The positionof the block b in the picture P3 is equivalent to the position of theblock a in the picture B2 (the block b is hereinafter referred to as a“co-located block” of the block a). The motion vector vb has alreadybeen used for coding the block b with reference to the picture P1. Theblock a is coded by bi-prediction using reference blocks obtained from aforward reference picture and a backward reference picture, that is, thepicture P1 and the picture P3 using motion vectors parallel to themotion vector vb. Specifically, the block a is coded using two motionvector: one is a motion vector vat for the picture P1; and the other isa motion vector vat for the picture P3.

Furthermore, merge mode has been being proposed as an inter predictionmode for coding of each block in a B-picture or a P-picture. In themerge mode, a block is coded using a motion vector and a referencepicture index which are copies of those used for coding of a neighboringblock of the block. In the coding of the block, the index and others ofthe neighboring block from which the index and others are copied areattached to a bitstream, so that the motion vector and reference pictureindex can be selected in decoding of the block.

FIG. 3 shows exemplary motion vectors and reference picture indices of aneighboring block for use in the merge mode. Referring to FIG. 3, acoded block located to the immediate left of a current block is aneighboring block A. A coded block located immediately above the currentblock is a neighboring block B. A coded block located immediately aboveto the right of the current block is a neighboring block C. A codedblock located immediately below to the left of the current block is aneighboring block D.

In FIG. 3, the neighboring block A is a block coded by uni-prediction inthe prediction direction 0, and has a motion vector MvL0_A for theprediction direction 0 pointing to a reference picture indicated by areference picture index RefL0_A for the prediction direction 0. The MvL0is a motion vector pointing to a reference picture indicated in thereference picture list 0 (L0).

The MvL1 is a motion vector pointing to a reference picture indicated inthe reference picture list 1 (L1). The neighboring block B is a blockcoded by uni-prediction in the prediction direction 1, and has a motionvector MvL1_B for the prediction direction 1 pointing to a referencepicture indicated by a reference picture index RefL1_B for theprediction direction 1. The neighboring block C is a block coded byintra prediction. The neighboring block D is a block coded byuni-prediction in the prediction direction 0, and has a motion vectorMvL0_D for the prediction direction 0 pointing to a reference pictureindicated by a reference picture index RefL0_D for the predictiondirection 0.

In the case shown in FIG. 3, a set of a motion vector and a referencepicture index with which the current block is coded with the highestcoding efficiency is selected from among the sets of a motion vector anda reference picture index of the neighboring blocks A, B, C, and D, andthe set of a motion vector and a reference picture index calculatedusing the co-located block for the temporal motion vector predictionmode. Then, a merging block candidate index indicating the selectedneighboring block is attached to a bitstream. For example, when theneighboring block A is selected, the current block is coded using themotion vector MvL0_A for the prediction direction 0 and the referencepicture index RefL0_A. Then, as shown in FIG. 4, only a value of 0 whichis the value of the merging block candidate index indicating the use ofthe neighboring block A is attached to a bitstream. The amount ofinformation on a motion vector and a reference picture index is therebyreduced.

FIG. 4 shows an exemplary merging block candidate list.

As shown in FIG. 4, in the merge mode, a candidate which cannot be usedfor merging (hereinafter referred to as a unusable-for-mergingcandidate) and a candidate having a set of a prediction direction, amotion vector, and a reference picture index identical to that of anyother candidate (hereinafter referred to as an identical candidate) areexcluded from the merging block candidates. Furthermore, instead of theexcluded candidate, a new candidate is added which, for example, is azero vector candidate. The zero vector candidate is a set of a motionvector of a horizontal component of 0 and a vertical component of zeroand a reference picture index having a value of 0. Such increase in thetotal number of candidates usable for merging increases codingefficiency.

Here, a “candidate unusable for merging” means that (1) the mergingblock candidate has been coded using intra prediction, (2) the mergingblock candidate is outside the boundary of the slice or the pictureincluding the current block, or (3) the merging block candidate is yetto be coded. In the example shown in FIG. 4, the neighboring block C iscoded using intra picture prediction, and therefore the neighboringblock C as a merging block candidate is an unusable-for-mergingcandidate and is thus excluded from the merging block candidate list.FIG. 4 also shows a parameter five_minus_max_num_merge_cand. This is aparameter for calculation of a merging block candidate list size (thetotal number of merging block candidates) and is to be attached to abitstream as a parameter included in header information such as a sliceheader, a sequence parameter set (SPS), or a picture parameter set(PPS). A merging block candidate list size is calculated by subtractingthe value of five_minus_max_num_merge_cand from 5.

FIG. 5 shows a relationship between a merging block candidate list sizeand bit sequences assigned to merging block candidate indices.

Merging block candidate indices are coded by variable-length codingwhich is performed by assigning bit sequences to the merging blockcandidate indices according to the size of each merging block candidatelist as shown in FIG. 5. Thus, in the merge mode, the length of a bitsequence assigned to a merging block candidate index depends on amerging block candidate list size so that the amount of code can bereduced.

There is another mode having been proposed as an inter prediction modefor coding of each block in a B-picture or a P-picture. The mode isreferred to as skip mode. In the skip mode, a block is coded in the samemanner as in the merge mode, using a motion vector and a referencepicture index copied from a neighboring block of the block withreference to a merging block candidate list created as shown in FIG. 4.When all resultant prediction errors turn out to be zero for the block,a skip flag is set to have a value of 1, and the skip flag and a mergingblock candidate index are attached to a bitstream. This is a way how theskip mode has been applied.

However, there is a problem with the conventional skip mode in which amotion vector for a current block to be coded is copied from a motionvector of merging block candidates. For this reason, coding efficiencydecreases in the skip mode because motion vectors cannot be settled tozero vectors due to noise even when, for example, consecutive stillpictures are coded using inter prediction.

In order to address the problem, provided is a moving picture codingmethod according to an aspect of the present disclosure which is amethod of merging a prediction direction, a motion vector, and areference picture index of at least one merging candidate to code acurrent block, and the method includes: making a determination as towhether or not to code all blocks in a current picture in the skip mode;setting, based on a result of the determination, a first flag indicatingwhether or not a temporally neighboring block which is included in apicture different from the current picture and temporally neighbors thecurrent block is to be referenced; setting, based on the result of thedetermination, a value of a parameter for determining a total number ofmerging candidates; setting, based on the result of the determination, asecond flag for each block included in the current picture, the secondflag indicating whether or not the block is to be coded in the skipmode; determining, based on the first flag and the total number of themerging candidates, the at least one merging candidate from among one ormore candidates including a neighboring block which is either a blockspatially neighboring the current block in a picture including thecurrent block or a temporally neighboring block included in the picturedifferent from the current picture, the determined at least one mergingcandidate being at least one candidate usable for the merging; selectinga merging candidate to be used for coding of the current block fromamong the determined at least one merging candidate; and coding an indexwhich indicates the selected merging candidate and attaching the codedindex to a bitstream, according to the total number of the mergingcandidates.

With this, the first flag, the parameter, and the second flag is setbased on a result of the determination as to whether or not all blocksin a current picture is to be coded in the skip mode. This enablessettling motion vectors in the skip mode using merging block candidates(merging candidates) to zero vectors. As a result, coding efficiency isincreased.

Furthermore, when the determination made in the making of thedetermination is that all the blocks in the current picture are to becoded in the skip mode, in the setting of the first flag, the first flagmay be set to have a value to indicate that the temporally neighboringblock is not to be referenced.

Furthermore, when the determination made in the making of thedetermination is that all the blocks in the current picture are to becoded in the skip mode, in the setting of the value of the parameter,the value of the parameter may be set to cause the total number of themerging candidates to be determined to be one.

Furthermore, when the determination made in the making of thedetermination is that all the blocks in the current picture are to becoded in the skip mode, in the setting of the second flag, the secondflag may be set, for each block in the current picture, to indicate thatthe block is to be coded in the skip mode.

Furthermore, in the making of the determination, a picture skip flagwhich indicates the result of the determination may be attached to thebitstream, in the setting of the first flag, the first flag may be setbased on the picture skip flag, in the setting of the value of theparameter, the value of the parameter may be set based on the pictureskip flag, and in the setting of the second flag, the second flag may beset for each block in the current picture based on the picture skipflag.

Furthermore, in the setting of the first flag, when the picture skipflag indicates that all the blocks in the current picture are to becoded in the skip mode, the first flag may be set to have a value toindicate that the temporally neighboring block of the current block isnot to be referenced, and the first flag may not be attached to thebitstream, and when the picture skip flag indicates that not all theblocks in the current picture are to be coded in the skip mode, thefirst flag may be attached to the bitstream.

Furthermore, in the setting of the value of the parameter, when thepicture skip flag indicates that all the blocks in the current pictureare to be coded in the skip mode, the value of the parameter may be setto cause the total number of the merging candidates to be determined tobe one, and the parameter may not be attached to the bitstream, and whenthe picture skip flag indicates that not all the blocks in the currentpicture are to be coded in the skip mode, the parameter may be attachedto the bitstream.

Furthermore, when the picture skip flag indicates that all the blocks inthe current picture are to be coded in the skip mode, the second flagmay be set, for each block in the current picture, to indicate that theblock is to be coded in the skip mode, and the second flag may not beattached to the bitstream, and when the picture skip flag indicates thatnot all the blocks in the current picture are to be coded in the skipmode, the second flag set for each block in the current picture may beattached to the bitstream.

Furthermore, in the coding of the index, when the total number of themerging candidates is one, the attaching of the coded index whichindicates the selected merging candidate to the bitstream may beomitted.

In order to address the problem, provided is a moving picture decodingmethod according to an aspect of the present disclosure which is amethod of merging a prediction direction, a motion vector, and areference picture index of at least one merging candidate to decode acurrent block, and the method includes: decoding a first flag indicatingwhether or not a temporally neighboring block which is included in apicture different from the current picture and temporally neighbors thecurrent block is to be referenced; decoding a value of a parameter fordetermining a total number of merging candidates; decoding a second flagwhich is set for each block included in the current picture andindicates whether or not the block is to be decoded in the skip mode;determining, based on the first flag and the total number of the mergingcandidates, the at least one merging candidate from among one or morecandidates including a neighboring block which is either a blockspatially neighboring the current block in a picture including thecurrent block and or a temporally neighboring block included in thepicture different from the current picture, the determined at least onemerging candidate being at least one candidate usable for the merging;and decoding, according to the total number of the merging candidates,an index which indicates a merging candidate to be used for decoding ofthe current block, the merging candidate to be used for decoding of thecurrent block being among the at least one determined merging candidate.

Furthermore, the moving picture decoding method may further include:decoding a picture skip flag which indicates whether or not all blocksin the current picture are to be decoded in the skip mode, wherein inthe decoding of the first flag, the first flag may be decoded based onthe picture skip flag, in the decoding of the value of the parameter,the value of the parameter may be decoded based on the picture skipflag, in the decoding of the second flag, the second flag set for eachblock included in the current picture may be decoded based on thepicture skip flag.

Furthermore, in the decoding of the first flag, when the picture skipflag has a value of one, the decoding of the first flag may be omitted.

Furthermore, in the decoding of the value of the parameter, when thepicture skip flag has a value of one, the decoding of the value of theparameter may be omitted.

Furthermore, in the decoding of the second flag, when the picture skipflag has a value of one, the decoding of the second flag may be omitted.

Furthermore, in the decoding of the index, when the total number of themerging candidates is one, the decoding of the index which indicates themerging candidate to be used for decoding of the current block may beomitted.

These general and specific aspects can be implemented as a system, amethod, an integrated circuit, a computer program, a computer-readablerecording medium such as a CD-ROM, or as any combination of a system, amethod, an integrated circuit, a computer program, and acomputer-readable recording medium.

Hereinafter, embodiments will be concretely described with reference tothe drawings.

Each of the embodiments described below shows a general or specificexample. The numerical values, shapes, materials, constituent elements,the arrangement and connection of the constituent elements, processingsteps, the order of the steps etc. shown in the following embodimentsare mere examples, and therefore do not limit the scope of claims.Therefore, among the constituent elements in the following exemplaryembodiments, constituent elements not recited in an independent claimdefining the most generic part of the inventive concept are described asoptional constituent elements.

Embodiment 1

FIG. 6 is a block diagram showing a configuration of a moving picturecoding apparatus in which a moving picture coding method according toEmbodiment 1 is used.

As shown in FIG. 6, the moving picture coding apparatus 100 includes asubtractor 101, an orthogonal transformation unit 102, a quantizationunit 103, an inverse-quantization unit 104, an inverse-orthogonaltransformation unit 105, an adder 106, block memory 107, frame memory108, an intra prediction unit 109, an inter prediction unit 110, aninter prediction control unit 111, a picture-type determination unit112, a switch 113, a merging block candidate calculation unit 114,colPic memory 115, a variable-length coding unit 116, and apicture-skipping determination unit 117.

The subtractor 101 generates prediction error data by subtracting, on ablock-by-block basis, prediction image data from input image dataincluded in an input image sequence.

The orthogonal transformation unit 102 transforms the generatedprediction error data from picture domain into frequency domain.

The quantization unit 103 quantizes the prediction error datatransformed into the frequency domain.

The inverse-quantization unit 104 inverse-quantizes the prediction errordata quantized by the quantization unit 103.

The inverse-orthogonal transformation unit 105 transforms theinverse-quantized prediction error data from frequency domain intopicture domain.

The adder 106 generates reconstructed image data by adding, on ablock-by-block basis, prediction image data and the prediction errordata inverse-quantized by the inverse-orthogonal transformation unit105.

The block memory 107 stores the reconstructed image data in units of ablock.

The frame memory 108 stores the reconstructed image data in units of aframe.

The picture-type determination unit 112 determines in which of thepicture types of I-picture, B-picture, and P-picture the input imagedata is to be coded. Then, the picture-type determination unit 112generates picture-type information indicating the determined picturetype.

The intra prediction unit 109 generates intra prediction image data of acurrent block by performing intra prediction using reconstructed imagedata stored in the block memory 107 in units of a block.

The inter prediction unit 110 generates inter prediction image data(prediction image) of a current block by performing inter predictionusing reconstructed image data stored in the frame memory 108 in unitsof a frame and a motion vector derived by processing such as motionestimation.

When a current block is coded using intra prediction, the switch 113outputs, as prediction image data of the current block, intra predictionimage data generated by the intra prediction unit 109 to the subtractor101 and the adder 106. When a current block is coded using interprediction, the switch 113 outputs, as prediction image data of thecurrent block, inter prediction image data generated by the interprediction unit 110 to the subtractor 101 and the adder 106.

The picture-skipping determination unit 117 calculates a value of apicture skip flag using a method described later, and outputs thepicture skip flag having the calculated value to the merging blockcandidate calculation unit 114. When the picture skip flag is set tohave a value of 1, all blocks in a current picture is coded in the skipmode in which zero vectors are used as motion vectors.

By use of a method described later, the merging block candidatecalculation unit 114 derives merging block candidates (mergingcandidates) for the merge mode and the skip mode, using motion vectorsand others of neighboring blocks of a current block and a motion vectorand others of a co-located block (colPic information). The colPicinformation is stored in the colPic memory 115. Furthermore, the mergingblock candidate calculation unit 114 calculates a merging blockcandidate list size (the total number of merging candidates).Furthermore, the merging block candidate calculation unit 114 assignsmerging block candidate indices to the derived merging block candidates.Then, the merging block candidate calculation unit 114 transmits themerging block candidates and merging block candidate indices to theinter prediction control unit 111. Furthermore, the merging blockcandidate calculation unit 114 transmits a calculated merging blockcandidate list size (specifically, five_minus_max_num_merge_cand) to thevariable-length coding unit 116.

The inter prediction control unit 111 determines, according to the valueof the picture skip flag, whether a current block is to be coded in theskip mode, the motion vector coding mode (motion vector estimationmode), or the merge mode. In the motion vector coding mode, the currentblock is coded using a motion vector derived by motion estimation. Inother words, the inter prediction control unit 111 determines aprediction mode (a coding mode or a prediction coding mode) to beapplied to a current block from among the skip mode, motion vectorcoding mode, and merge mode. Furthermore, when the determined predictionmode is the skip mode, the inter prediction control unit 111 transmits,to the variable-length-coding unit 116, a skip flag (a second flag)indicating whether or not the skip mode is applied and a merging blockcandidate index corresponding to a determined merging block candidate.Furthermore, the inter prediction control unit 111 transfers colPicinformation including a motion vector of a current block to the colPicmemory 115.

The variable-length coding unit 116 generates a bitstream by performingvariable-length coding on the quantized prediction error data, the skipflag, and the picture-type information (picture type). Furthermore, thevariable-length coding unit 116 performs variable-length coding on amerging block candidate index to be used in coding, by assigning, to themerging block candidate index, a bit sequence according to a mergingblock candidate list size.

FIG. 7 is a flowchart showing a moving picture coding method performedby the image coding apparatus 100 according to Embodiment 1. First, inS100, a picture skip determination is performed using a method describedlater to determine the value of a picture skip flag. In S101, whether ornot the picture skip flag has a value of 1 is determined. When theresult of the determination is true (S101, Yes),enable_temporal_mvp_flag (a first flag) is set to have a value of 0 inS102. The flag of enable_temporal_mvp_flag indicates whether or not amotion vector in the temporal motion vector prediction mode is to becalculated from a motion vector of a co-located block. Then, the flag isattached to header information such as a sequence parameter set (SPS), apicture parameter set (PPS), a slice header, or the like. The flag ofenable_temporal_mvp_flag having a value of 1 indicates that a motionvector in the temporal motion vector prediction mode is to be calculatedfrom a motion vector of a co-located block and the co-located block isto be added to a merging block candidate list as a co-located mergingblock. The flag of enable_temporal_mvp_flag having a value of 0indicates that a motion vector in the temporal motion vector predictionmode is not to be calculated from a motion vector of a co-located block.In S103, five_minus_max_num_merge_cand is set to have a value of 4, andin S104, the above-described skip_flag is set to have a value of 1.

In this manner, when it is determined in S101 that a picture skip flaghas a value of 1, enable_temporal_mvp_flag is set to have a value of 0,five_minus_max_num_merge_cand is set to have a value of 4, and skip_flagis set to have a value of 1.

When the result of the determination in S101 is false (S101, No),enable_temporal_mvp_flag is set to have a value of 1 in S110,five_minus_max_num_merge_cand is set to have a value of 0 in S111, andskip_flag is set to have a value of 0 in S112. In Embodiment 1, thevalue which five_minus_max_num_merge_cand is set to have in S111 is notlimited to 0 and may be set to have a value other than 0.

In S105, by use of a method described later, merging block candidatesare generated from neighboring blocks and a co-located block of acurrent block, and a merging block candidate list size is calculated.For example, in the case shown in FIG. 3, merging block candidates ofsets of a motion vector and reference picture index of a current blockto be coded are generated from the neighboring block A, B, C, and D anda co-located merging block having a motion vector and others calculatedfrom a motion vector of the co-located block in temporal motion vectorprediction mode. When five_minus_max_num_merge_cand has a value of 0,that is, when a merging block candidate list size is 5, each mergingblock candidate is assigned with a merging block candidate index asshown in as shown in FIG. 4. When five_minus_max_num_merge_cand has avalue of 4, that is, when a merging block candidate list size is 1, onemerging block candidate is assigned with a merging block candidate indexas shown in FIG. 9.

Merging block candidate indices of smaller values are assigned withshorter codes. In other words, the smaller the value of a merging blockcandidate index is, the smaller the necessary information amount is. Onthe other hand, the larger the value of a merging block candidate indexis, the larger the necessary information amount is. Accordingly, codingefficiency will be increased when merging block candidate indices havingsmaller values are assigned to merging block candidates which are morelikely to be sets of a motion vector and a reference picture index. Forexample, this can be achieved by counting the total number of times ofbeing selected as a merging block for each merging block candidate andassigning a merging block candidate index having a smaller value to ablock with a larger total number of the times. Specifically, this can beachieved by identifying a merging block selected from among neighboringblocks and assigning a merging block candidate index having a smallervalue to the identified merging block when a current block is coded.

When a merging block candidate does not have information such as amotion vector, that is, for example, when the merging block is a blockcoded using intra prediction, the merging block is located outside theboundary of a picture or a slice, or the merging block is yet to becoded), it is determined that the merging block candidate is not usableas a merging block candidate. In Embodiment 1, a merging block candidateunusable as a merging block candidate is referred to as anunusable-for-merging candidate, and a merging block candidate usable asa merging block candidate is referred to as a usable-for-mergingcandidate. In addition, a merging block candidate sharing a motionvector, a reference picture index, and a prediction direction with anyother merging block candidate is referred to as an identical candidate.In the case shown in FIG. 3, the neighboring block C is anunusable-for-merging candidate because it is a block coded using intraprediction.

In S106, skip_flag is coded by variable-length coding. In S107, whetheror not skip_flag has a value of 1 is determined. When the result of thedetermination in S107 is true (S107, Yes), the current block is coded inthe skip mode in S108. More specifically, a merging block candidateindex of a merging block candidate to be used for generation of aprediction picture in the skip mode is coded by variable-length codingaccording to a merging block candidate list size. When a merging blockcandidate list size is 1, the merging block candidate index can beestimated to have a value of 0. In this case, it is possible to attachno merging block candidate index to a bitstream. This will furtherincrease coding efficiency. When the result of the determination in S107is false (S107, No), in S109, the current block is coded in a predictioncoding mode determined based on a result of processing such ascomparison between prediction error of an inter prediction imagegenerated using a motion vector derived by motion estimation andprediction error of a prediction picture generated using a merging blockcandidate in the merge mode. In other words, the current block is codedin the merge mode or the motion vector coding mode.

In Embodiment 1, as exemplified in FIG. 4, the merging block candidateindex corresponding to the neighboring block A has a value of 0, themerging block candidate index corresponding to the neighboring block Bhas a value of 1, the merging block candidate index corresponding to theco-located merging block has a value of 2, and the merging blockcandidate index corresponding to the neighboring block D has a value of3. However, assignment of merging block candidate indices is not limitedto the example. For example, when a new candidate such as a zero vectorcandidate is added using a method described later, smaller values may beassigned to preexistent merging block candidates and a larger value tothe new candidate so that the preexistent merging block candidates areprioritized. Moreover, the merging block candidates are not limited tothe neighboring blocks A, B, C, or D. For example, a neighboring blocklocated above the lower left neighboring block D may be also used as amerging block candidate. Optionally, it is not necessary to use all theneighboring blocks. For example, only the neighboring blocks A and B maybe used as merging block candidates.

Moreover, attaching a merging block candidate index to a bitstream inS108 in FIG. 7 is not necessary in Embodiment 1. Optionally, attaching amerging block candidate index may be omitted when a merging blockcandidate list size is 1. The amount of information on merging blockcandidate indices is thereby reduced.

The processing step of S100 is performed by the picture-skippingdetermination unit 117, and the processing steps of S100 to S105 andS110 to S112 by the merging block candidate calculation unit 114, for anexample. The processing step of S106 is performed by thevariable-length-coding unit 116, and the processing steps of S107 toS109 by a group of constituent elements including the inter predictionunit 110 and the inter prediction control unit 111, for an example.

FIG. 8 is a flowchart showing details of the processing in S100 in FIG.7. More specifically, this flowchart shows an example of processing fordetermining the value of a picture skip flag by the picture-skippingdetermination unit 117 detecting a motion amount of a current picture tobe coded. The processing will be described in detail with reference toFIG. 8.

In S100 a, a motion amount between whole pictures is estimated byprocessing such as block-matching between a current picture and areference picture. The motion amount of a whole picture may becalculated by any method, for example, by calculating from an averagevalue of motion vectors used for coding of a coded picture. In S100 b,whether or not the motion amount of a whole picture is below or equal toa predetermined threshold value is determined. When the result of thedetermination is true (S100 b, Yes), the current picture is determinedas a picture with less motion, and the picture skip flag is set to havea value of 1 in S100 c. When the result of the determination in S100 bis false (S100 b, No), the picture skip flag is set to have a value of 0in S100 d. A picture skip flag is thus set to have a value according toa motion amount of a whole picture, so that, for example, picture skipflags can be set to have a value of 1 when a current picture is one ofconsecutive still pictures. Picture skipping is thus performed toincrease coding efficiency.

FIG. 10 is a flowchart showing details of the processing in S105 in FIG.7. In other words, this flowchart shows a method of calculating mergingblock candidates and a merging block candidate list size. FIG. 10 willbe described below.

In S105 a, a merging block candidate list size is calculated usingfive_minus_max_num_merge_cand. In S105 b, it is determined whether it istrue either that a merging block candidate [N] is not a co-locatedmerging block or that enable_temporal_mvp_flag has a value of 1. Whenthe result of the determination is true (S105 b, Yes), in S105 c,whether or not the merging block candidate [N] is usable for merging isdetermined, and the total number of usable-for-merging candidates isupdated. The parameter N denotes an index value to identify a mergingblock candidate and may have a value from 0 to 4 in Embodiment 1. Morespecifically, the neighboring block A in FIG. 3 is assigned to a mergingblock candidate [0], the neighboring block B in FIG. 3 to the mergingblock candidate [1], a co-located merging block to a merging blockcandidate [2], the neighboring block C in FIG. 3 to the merging blockcandidate [3], and the neighboring block D in FIG. 3 to the mergingblock candidate [4]. Whether or not each merging block candidate [N] isusable for merging is determined by determining whether or not it istrue that the merging block candidate [N] is a block coded by intrapicture prediction, a block located outside the boundary of a picture ora slice, or a block yet to be coded. When the result of thisdetermination is true, the merging block candidate [N] is determined tobe an unusable-for-merging candidate. When the result of thisdetermination is false, the merging block candidate [N] is determined tobe a usable-for-merging candidate.

In S105 d, a set of a motion vector, a reference picture index, and aprediction direction of the merging block candidate [N] is obtained andadded to the merging block candidate list. When the result of thedetermination in S105 b is false, that is, when the merging blockcandidate [N] is a co-located merging block and enable_temporal_mvp_flaghas a value of 0 (S105, No), the merging block candidate [N] is notadded to the merging block candidate list.

In S105 e, it is determined whether or not the total number ofusable-for-merging candidates calculated by iteratively performing theprocessing steps of S105 b to S105 d is smaller than the merging blockcandidate list size. When the result of this determination is true (S105e, Yes), a zero vector candidate is added as a new candidate to themerging block candidates in S105 f. Here, the zero vector candidate is acandidate having a motion vector of a horizontal component of 0 and avertical component of 0 and a reference picture index having a value of0. In S105 g, a merging block candidate index is assigned to a candidatewithin the merging block candidate list size. Here, when a new candidateis added, merging block candidate indices may be reassigned so that themerging block candidate indices having smaller values are assigned topreexistent merging block candidates. In other words, the preexistentmerging block candidates may be prioritized by, for example, assigning amerging block candidate index having a larger value to a new candidate.The amount of codes for merging block candidate indices is therebyreduced.

FIG. 11 shows a motion vector of each block for the skip mode when thepicture skip flag has a value of 1. More specifically, FIG. 11 shows anexample in which a picture skip flag is set to have a value of 1 in S100in FIG. 7 and motion vectors of the blocks for the skip mode arecalculated according to the flowcharts shown in FIG. 7 and FIG. 10.

In the case of coding of a block A in the upper-left corner of thepicture for which the picture skip flag is set to have a value of 1, amerging block candidate list size is 1 and its neighboring blocks areoutside the boundary of the picture. Accordingly, all blocks areunusable for merging and enable_temporal_mvp_flag is set to have a valueof 0. Thus, only a zero vector candidate is added to the merging blockcandidate list. As a result, the block A is coded in the skip mode usingthe zero vector.

In the case of coding of a block B in the uppermost row of the picturefor which the picture skip flag is set to have a value of 1, a mergingblock candidate list size is 1, only a neighboring block left to thecurrent block is usable for merging, and enable_temporal_mvp_flag is setto have a value of 0. Accordingly, only the motion vector of the blockA, that is, the zero vector candidate is added to the merging blockcandidate list. As a result, the block B is coded in the skip mode usingthe zero vector.

In the case of coding of a block C in the leftmost column of the picturefor which the picture skip flag is set to have a value of 1, a mergingblock candidate list size is 1, only its upper neighboring block isusable for merging, and enable_temporal_mvp_flag is set to have a valueof 0. Accordingly, only the motion vector of the block A, that is, thezero vector candidate is added to the merging block candidate list. As aresult, the block C is coded in the skip mode using the zero vector.

In the case of coding of a block D for which the picture skip flag isset to have a value of 1, a merging block candidate list size is 1, aneighboring block left to the current block is usable for merging, andenable_temporal_mvp_flag is set to have a value of 0. Accordingly, onlythe motion vector of the block C, that is, the zero vector candidate isadded to the merging block candidate list. As a result, the block D iscoded in the skip mode using the zero vector.

In this manner, when the picture skip flag has a value of 1,enable_temporal_mvp_flag is set to have a value of 0, thefive_minus_max_num_merge_cand is set to have a value of 4 (the mergingblock candidate list size to a value of 1), and skip_flag is set to havea value of 1 so that all the blocks in the picture can be coded using azero vector in the skip mode.

In this manner, according to Embodiment 1, a picture skip flag is set tohave a value of 1 so that all blocks in a picture can be coded in theskip mode using a zero vector. This will increase coding efficiencyespecially for consecutive still pictures. More specifically, when apicture skip flag has a value of 1, setting enable_temporal_mvp_flag tohave a value of 0 and skip_flag to have a value of 1 enables coding allblocks in a picture in the skip mode using a zero vector. Furthermore,setting five_minus_max_num_merge_cand to have a value of 4 (the mergingblock candidate list size to have a value of 1) makes sending of amerging block candidate index unnecessary, so that coding efficiency inpicture skipping can be increased.

In Embodiment 1, five_minus_max_num_merge_cand is set to have a value of4 (a merging block candidate list size is set to have a value of 1) anda zero vector candidate among merging block candidates is used so thatall blocks in a picture are coded using the zero vector candidate in theskip mode, which is not limiting the present invention. For example,five_minus_max_num_merge_cand is set to have a value of 5 (a mergingblock candidate list size is set to have a value of 0). In this casewhere a merging block candidate list size is 0, coding is performed inthe skip mode using a zero vector so that no merging block candidate iscalculated. Coding may be thus performed on all blocks in a picture inthe skip mode using a zero vector while computational complexity isreduced.

In Embodiment 1, the merge mode is used in which a current block iscoded using a motion vector and a reference picture index copied from aneighboring block of a current block, which is not limiting the presentinvention. For example, a motion vector in the motion vector estimationmode may be coded using a merging block candidate list created as shownin FIG. 9. More specifically, a difference may be calculated bysubtracting a motion vector of a merging block candidate indicated by amerging block candidate index from a motion vector in the motion vectorestimation mode, and the difference and a merging block candidate indexmay be attached to a bitstream. Alternatively, a difference may becalculated by scaling a motion vector MV_Merge of a merging blockcandidate using a reference picture index RefIdx_ME in the motion vectorestimation mode and a reference picture index RefIdx_Merge of themerging block candidate and subtracting a motion vector scaledMV_Mergeof the merging block candidate obtained by the scaling from the motionvector in the motion vector estimation mode, and the difference and amerging block candidate index may be attached to a bitstream. EQ. 1shown below is an exemplary formula for the scaling.

scaledMV_Merge=MV_Merge×(POC(RefIdx_ME)−curPOC)/(POC(RefIdx_Merge)−curPOC)  (EQ.1)

Here, POC (RefIdx_ME) denotes the display order of a reference pictureindicated by a reference picture index RefIdx_ME. POC (RefIdx_Merge)denotes the display order of a reference picture indicated by areference picture index RefIdx_Merge. curPOC denotes the display orderof a current picture to be coded.

Embodiment 2

FIG. 12 is a block diagram showing an exemplary configuration of amoving picture decoding apparatus in which a moving picture decodingmethod according to Embodiment 2 is used.

For example, the moving picture decoding apparatus 300 decodes, on ablock-by-block basis, coded images included in a bitstream generated bythe moving picture coding apparatus 100 according to Embodiment 1. Asshown in FIG. 12, the moving picture decoding apparatus 300 includes avariable-length decoding unit 301, an inverse-quantization unit 302, aninverse-orthogonal transformation unit 303, an adder 304, block memory305, frame memory 306, an intra prediction unit 307, an inter predictionunit 308, an inter prediction control unit 309, a switch 310, a mergingblock candidate calculation unit 311, and colPic memory 312.

The variable-length decoding unit 301 obtains picture-type information(picture type), a skip flag, a merging block candidate list size(specifically, five_minus_max_num_merge_cand), and a quantizedcoefficient by performing variable-length decoding on an inputbitstream. Furthermore, the variable-length decoding unit 301 performsvariable-length decoding on a merging block candidate index using amerging block candidate list size.

The inverse-quantization unit 302 inverse-quantizes the quantizedcoefficient obtained by the variable-length decoding.

The inverse-orthogonal transformation unit 303 generates predictionerror data by transforming an orthogonal transform coefficient obtainedby the inverse quantization from frequency domain into picture domain.

The block memory 305 stores, in units of a block, a decoded imagesequence generated by adding the prediction error data and predictionimage data.

The frame memory 306 stores a decoded image sequence in units of aframe.

The intra prediction unit 307 generates prediction image data of acurrent block to be decoded, by performing intra prediction using thedecoded image sequence stored in the block memory 305 in units of ablock.

The inter prediction unit 308 generates inter prediction image data(prediction image) of a current block to be decoded, by performing interprediction using the decoded image sequence stored in the frame memory306 in units of a frame.

When a current block is decoded by intra prediction decoding, the switch310 outputs, as prediction image data of the current block, intraprediction image data generated by the intra prediction unit 307 to theadder 304. When a current block is decoded by inter prediction decoding,the switch 310 outputs, as prediction image data of the current block,inter prediction image data generated by the inter prediction unit 308to the adder 304.

The merging block candidate calculation unit 311 calculates a mergingblock candidate list size using a method described later and derivesmerging block candidates for merge mode and skip mode using motionvectors and others of neighboring blocks of a current block and a motionvector and others of a co-located block (colPic information) of thecurrent block stored in the colPic memory. Furthermore, the mergingblock candidate calculation unit 311 assigns merging block candidateindices to the derived merging block candidates, and transmits themerging block candidates and merging block candidate indices to theinter prediction control unit 309.

When the skip flag decoded has a value of “0”, the inter predictioncontrol unit 309 causes the inter prediction unit 308 to generate aninter prediction image using information for motion vector estimationmode or merge mode. When the skip flag has a value of “1”, the interprediction control unit 309 determines, based on a decoded merging blockcandidate index, a motion vector, a reference picture index, and aprediction direction for use in inter prediction from a plurality ofmerging block candidates. Then, the inter prediction control unit 309causes the inter prediction unit 308 to generate an inter predictionimage using the determined motion vector, reference picture index, andprediction direction. Furthermore, the inter prediction control unit 309transfers colPic information including the motion vector of the currentblock to the colPic memory 312.

Finally, the adder 304 generates a decoded image sequence by addingprediction image data and prediction error image data.

FIG. 13 is a flowchart showing a moving picture decoding methodperformed by the moving picture decoding apparatus 300 according toEmbodiment 2. First, in S300, enable_temporal_mvp_flag is decoded, andthen, in S301 five_minus_max_num_merge_cand is decoded. In S302, amethod as shown in FIG. 10 is performed to calculate a merging blockcandidate list size and generate merging block candidates fromneighboring blocks and a co-located block of a current block to bedecoded. In S303, variable-length decoding is performed on a mergingblock candidate index included in a bitstream using the calculatedmerging block candidate list size. When the merging block candidate listsize is 1, the merging block candidate index may be estimated to have avalue of 0 without decoding a merging block candidate index. In S304,decoding is performed on skip_flag in a bitstream. In S305, whether ornot skip_flag has a value of 1 is determined. When the result of thedetermination in S305 is true (S305, Yes), in S306, an inter predictionpicture is generated in the skip mode using a motion vector, a referencepicture index, and a prediction direction of a merging block candidateindicated by a merging block candidate index. In other words, thecurrent block is decoded in the skip mode. When the result of thedetermination in S305 is false (S305, No), in S307, an inter predictionpicture is generated using information for merge mode or motion vectorcoding mode. In other words, the current block is decoded in the mergemode or the motion vector coding mode.

The processing steps of S300, S301, S303, and S304 are performed by thevariable-length decoding unit 301, and the processing step of S303 bythe merging block candidate calculation unit 311, for an example. Theprocessing steps of S305 to S307 are performed by a group of constituentelements including the inter picture prediction control unit 309 and theinter prediction unit 308, for an example.

FIG. 14 shows exemplary syntax according to Embodiment 2. Specifically,the syntax is used for attaching enable_temporal_mvp_flag,five_minus_max_num_merge_cand and skip_flag to a bitstream.

In this manner, according to Embodiment 2, a picture skip flag is set tohave a value of 1 so that it is possible to appropriately decode abitstream generated by coding all blocks in a picture in the skip modeusing a zero vector, especially a bitstream of consecutive stillpictures coded with increased coding efficiency. More specifically, whena picture skip flag has a value of 1, enable_temporal_mvp_flag is set tohave a value of 0 and skip_flag is set to have a value of 1. By usingthis setting, it is possible to appropriately decode a bitstreamgenerated by coding all blocks in a picture in the skip mode using azero vector. Furthermore, when five_minus_max_num_merge_cand is set tohave a value of 4 (the merging block candidate list size is set to havea value of 1), a merging block candidate index need not be transmittedby the moving picture coding apparatus 100. Thus, the moving picturedecoding apparatus 300 in Embodiment 2 can appropriately decode abitstream coded with increased coding efficiency for picture skipping.

Embodiment 3

FIG. 15 is a block diagram showing a configuration of a moving picturecoding apparatus in which a moving picture coding method according toEmbodiment 3 is used. Embodiment 3 is different from Embodiment 1 onlyin that a picture skip flag is attached to a bitstream, and thereforedescription of the other points is omitted.

As shown in FIG. 15, the moving picture coding apparatus 100 a includesa subtractor 101, an orthogonal transformation unit 102, a quantizationunit 103, an inverse-quantization unit 104, an inverse-orthogonaltransformation unit 105, an adder 106, block memory 107, frame memory108, an intra prediction unit 109, an inter prediction unit 110, aninter prediction control unit 111, a picture-type determination unit112, a switch 113, a merging block candidate calculation unit 114,colPic memory 115, a variable-length coding unit 116 a, and apicture-skipping determination unit 117.

The picture-skipping determination unit 117 calculates a value of apicture skip flag using a method as shown in FIG. 8. When the pictureskip flag has a value of 1, all blocks in a current picture is coded inthe skip mode in which zero vectors are used as motion vectors. Thepicture-skipping determination unit 117 outputs the picture skip flaghaving the calculated value to the merging block candidate calculationunit 114 and the variable-length-coding unit 116 a.

By use of a method described later, the merging block candidatecalculation unit 114 derives merging block candidates for the merge modeand the skip mode using motion vectors and others of neighboring blocksof a current block and a motion vector and others of the co-locatedblock (colPic information) stored in the colPic memory 115. Furthermore,the merging block candidate calculation unit 114 calculates a mergingblock candidate list size. Furthermore, the merging block candidatecalculation unit 114 assigns merging block candidate indices to thederived merging block candidates. Then, the merging block candidatecalculation unit 114 transmits the merging block candidates and mergingblock candidate indices to the inter prediction control unit 111.Furthermore, the merging block candidate calculation unit 114 transmitsthe calculated merging block candidate list size to the variable-lengthcoding unit 116 a.

The variable-length-coding unit 116 a performs variable-length codingnot only on a skip flag, a merging block candidate index, picture type,and the merging block candidate list size (specificallyfive_minus_max_num_merge_cand) but also on a picture skip flag.

FIG. 16 is a flowchart showing the moving picture coding methodperformed by the moving picture coding apparatus 100 a according toEmbodiment 3. First, in S500, a picture skipping determination isperformed using the method as shown in FIG. 8 to determine a value of apicture skip flag. Then, the picture skip flag is attached to a header.In S501, whether or not the picture skip flag has a value of 1 isdetermined. When the result of the determination is true (S501, Yes),enable_temporal_mvp_flag is set to have a value of 0 in S502. In S503,five_minus_max_num_merge_cand is set to have a value of 4, and in S504,skip_flag is set to have a value of 1.

In this manner, when it is determined in S501 that a picture skip flaghas a value of 1, enable_temporal_mvp_flag is set to have a value of 0,and five_minus_max_num_merge_cand is set to have a value of 4, andskip_flag is set to have a value of 1.

When the result of the determination in S501 is false (S501, No),enable_temporal_mvp_flag is set to have a value of 1 and attached to aheader in S510, and five_minus_max_num_merge_cand is set to have a valueof 0 and attached to a header in S511. Next, in S512, skip_flag is setto have a value of 0.

In this manner, coding efficiency can be increased by omitting attachingenable_temporal_mvp_flag and five_minus_max_num_merge_cand to abitstream when picture skipping is performed (S501, Yes). In Embodiment3, the value which five_minus_max_num_merge_cand is set to have in S511is not limited to 0 and may be set to have a value other than 0.

In S505, the method shown in FIG. 10 is performed to generate mergingblock candidates from neighboring blocks and calculated a co-locatedblock of a current block, and a merging block candidate list size. InS506, skip_flag is coded by variable-length coding according to thevalue of the picture skip flag. More specifically, when picture skipflag has a value of 1, skip_flag can be estimated to have a value of 1,and thus skip_flag is not attached to a bitstream. When a picture skipflag has a value of 0, skip_flag is coded by variable-length coding andattached to a bitstream. In this manner, attaching skip_flag to abitstream can be omitted when picture skipping is performed, so thatcoding efficiency can be increased.

In S507, whether or not skip_flag has a value of 1 is determined. Whenthe result of the determination in S507 is true (S507, Yes), the currentblock is coded in the skip mode in S508. More specifically, a mergingblock candidate index of a merging block candidate to be used forgeneration of a prediction picture in the skip mode is coded byvariable-length coding according to a merging block candidate list size.When a merging block candidate list size is 1, the merging blockcandidate index can be estimated to have a value of 0. In this case, itis possible to attach no merging block candidate index to a bitstream.This will further increase coding efficiency. When the result of thedetermination in S507 is false (S507, No), in S509, the current block iscoded in the prediction coding mode determined based on a result ofprocessing such as comparison between prediction error of an interprediction image generated using a motion vector derived by motionestimation and prediction error of a prediction picture generated usinga merging block candidate. In other words, the current block is coded inthe merge mode or the motion vector coding mode.

The processing step of S500 is performed by the picture-skippingdetermination unit 117 and the variable-length-coding unit 116 a, andthe processing steps of S501 to S505 and S510 to S512 by the mergingblock candidate calculation unit 114 and the variable-length-coding unit116 a, for an example. The processing step of S506 is performed by thevariable-length-coding unit 116 a and the processing steps of S507 toS509 by a group of constituent elements including the inter predictionunit 110 and the inter prediction control unit 111, for an example.

In Embodiment 3, as exemplified in FIG. 4, the merging block candidateindex corresponding to the neighboring block A has a value of 0, themerging block candidate index corresponding to the neighboring block Bhas a value of 1, the merging block candidate index corresponding to theco-located merging block has a value of 2, and the merging blockcandidate index corresponding to the neighboring block D has a value of3. However, assignment of merging block candidate indices is not limitedto the example. For example, when a new candidate such as a zero vectorcandidate is added using a method described later, smaller values may beassigned to preexistent merging block candidates and a larger value tothe new candidate so that the preexistent merging block candidates areprioritized. Moreover, the merging block candidates are not limited tothe neighboring blocks A, B, C, or D. For example, a neighboring blocklocated above the lower left neighboring block D may be also used as amerging block candidate. Optionally, it is not necessary to use all theneighboring blocks. For example, only the neighboring blocks A and B maybe used as merging block candidates.

Moreover, attaching a merging block candidate index to a bitstream inS508 in FIG. 16 is not necessary in Embodiment 3. Optionally, attachinga merging block candidate index may be omitted when a merging blockcandidate list size is 1. The amount of information on the merging blockcandidate index is thereby reduced.

In this manner, according to Embodiment 3, a picture skip flag is set tohave a value of 1 so that all blocks in a picture can be coded in theskip mode using a zero vector. This will increase coding efficiencyespecially for consecutive still pictures. More specifically, when apicture skip flag has a value of 1, setting enable_temporal_mvp_flag tohave a value of 0 and skip_flag to have a value of 1 enables coding allblocks in a picture in the skip mode using a zero vector. Furthermore,setting five_minus_max_num_merge_cand to have a value of 4 (the mergingblock candidate list size to have a value of 1) makes sending of amerging block candidate index unnecessary, so that coding efficiency inpicture skipping can be increased. Furthermore, coding efficiency can beincreased by omitting attaching skip_flag, enable_temporal_mvp_flag, andfive_minus_max_num_merge_cand to a bitstream when a picture skip flaghas a value of 1.

In Embodiment 3, five_minus_max_num_merge_cand is set to have a value of4 (a merging block candidate list size is set to have a value of 1) anda zero vector candidate among merging block candidates is used so thatall blocks in a picture are coded using the zero vector candidate in theskip mode, which is not limiting the present invention. For example,five_minus_max_num_merge_cand is set to have a value of 5 (a mergingblock candidate list size is set to have a value of 0). In this casewhere a merging block candidate list size is 0, coding is performed inthe skip mode using a zero vector so that no merging block candidate iscalculated. Coding may be thus performed on all blocks in a picture inthe skip mode using a zero vector while computational complexity isreduced.

Embodiment 4

FIG. 17 is a block diagram showing an exemplary configuration of amoving picture decoding apparatus in which a moving picture decodingmethod according to Embodiment 4 is used. Embodiment 4 is different fromEmbodiment 2 only in that a picture skip flag a is decoded from abitstream, and therefore description of the other points is omitted.

Specifically, for example, the moving picture decoding apparatus 300 adecodes, on a block-by-block basis, coded images included in a bitstreamgenerated by the moving picture coding apparatus 100 a according toEmbodiment 3. As shown in FIG. 17, the moving picture decoding apparatus300 a 400 includes a variable-length decoding unit 301 a, aninverse-quantization unit 302, an inverse-orthogonal transformation unit303, an adder 304, block memory 305, frame memory 306, an intraprediction unit 307, an inter prediction unit 308, an inter predictioncontrol unit 309, a switch 310, a merging block candidate calculationunit 311, and colPic memory 312.

The variable-length decoding unit 301 a obtains picture-type information(picture type), a picture skip flag, a skip flag, a merging blockcandidate list size (specifically, five_minus_max_num_merge_cand), and aquantized coefficient by performing variable-length decoding on an inputbitstream. Furthermore, the variable-length decoding unit 301 a obtainsa merging block candidate index by performing variable-length decodingusing a merging block candidate list size.

The merging block candidate calculation unit 311 calculates a mergingblock candidate list size using a method described later and derivesmerging block candidates for merge mode and skip mode using motionvectors and others of neighboring blocks of a current block and a motionvector and others of a co-located block (colPic information) of thecurrent block stored in the colPic memory. Furthermore, the mergingblock candidate calculation unit 311 assigns merging block candidateindices to the derived merging block candidates, and transmits themerging block candidates and merging block candidate indices to theinter prediction control unit 309.

When the skip flag decoded has a value of “0”, the inter predictioncontrol unit 309 causes the inter prediction unit 308 to generate aninter prediction image using information for motion vector estimationmode or merge mode. When the skip flag has a value of “1”, the interprediction control unit 309 determines, based on a decoded merging blockcandidate index, a motion vector, a reference picture index, and aprediction direction for use in inter prediction from a plurality ofmerging block candidates. Then, the inter prediction control unit 309causes the inter prediction unit 308 to generate an inter predictionimage using the determined motion vector, reference picture index, andprediction direction. Furthermore, the inter prediction control unit 309transfers colPic information including the motion vector of the currentblock to the colPic memory 312.

Finally, the adder 304 generates decoded image sequence by addingprediction image data and prediction error image data.

FIG. 18 is a flowchart showing a moving picture decoding methodperformed by the moving picture decoding apparatus 300 a according toEmbodiment 4. First, in S700, a picture skip flag is decoded from abitstream. In S701, whether or not the picture skip flag has a value of0 is determined. When the result of the determination is true (S701,Yes), enable_temporal_mvp_flag is decoded in S702, andfive_minus_max_num_merge_cand is decoded in S703.

When the result of the determination in S701 is false (S701, No),enable_temporal_mvp_flag is set to have a value of 0 in S704, andfive_minus_max_num_merge_cand is set to have a value of 4 in S705. InS706, a method as shown in FIG. 10 is performed to calculate a mergingblock candidate list size and generate merging block candidates fromneighboring blocks and a co-located block of a current block to bedecoded. In S707, variable-length decoding is performed on a mergingblock candidate index included in a bitstream using the merging blockcandidate list size. When the merging block candidate list size is 1,the merging block candidate index may be estimated to have a value of 0without decoding a merging block candidate index. In S708, whether ornot the picture skip flag has a value of 0 is determined. When theresult of the determination is true (S708, Yes), skip_flag is decoded inS709. When the result of the determination in S708 is false (S708, No),skip_flag is set to have a value of 1 in S710. In S711, whether or notskip_flag has a value of 1 is determined. When the result of thedetermination in S711 is true (S711, Yes), in S712, an inter predictionpicture is generated in the skip mode using a motion vector, a referencepicture index, and a prediction direction of a merging block candidateindicated by a merging block candidate index. In other words, a currentblock is decoded in the skip mode. When the result of the determinationin S711 is false (S711, No), in S713, an inter prediction picture isgenerated using information for merge mode or motion vector coding mode.In other words, the current block is decoded in the merge mode or themotion vector coding mode.

The processing steps of S700 to S705 and S707 to S710 are performed bythe variable-length decoding unit 301 a, and the processing step of S706by the merging block candidate calculation unit 311, for an example. Theprocessing steps of S711 to S713 are performed by a group of constituentelements including the inter picture prediction control unit 309 and theinter prediction unit 308, for an example.

FIG. 19 shows exemplary syntax according to Embodiment 4. Specifically,the syntax is used for attaching a picture skip flag(picture_skip_flag), enable_temporal_mvp_flag,five_minus_max_num_merge_cand, and skip_flag to a bitstream. The pictureskip flag may be attached to a header of another type such as an SPS, aPPS or the like.

In this manner, according to Embodiment 4, a picture skip flag is set tohave a value of 1 so that a bitstream generated by coding all blocks ina picture in the skip mode using a zero vector, especially a bitstreamof consecutive still pictures coded with increased coding efficiency,can be appropriately decoded. More specifically, when a picture skipflag has a value of 1, enable_temporal_mvp_flag is set to have a valueof 0 and skip_flag is set to have a value of 1. By using this setting,it is possible to appropriately decode a bitstream generated by codingall blocks in a picture in the skip mode using a zero vector.Furthermore, when five_minus_max_num_merge_cand is set to have a valueof 4 (the merging block candidate list size is set to have a value of1), a merging block candidate index need not be transmitted by themoving picture coding apparatus 100 a. Thus, the moving picture decodingapparatus 300 a in Embodiment 4 can appropriately decode a bitstreamcoded with increased coding efficiency for picture skipping.Furthermore, when a picture skip flag has a value of 1, attachingskip_flag, enable_temporal_mvp_flag, and five_minus_max_num_merge_candto a bitstream is omitted. Thus, the moving picture decoding apparatus300 a in Embodiment 4 can appropriately decode a bitstream coded withcoding efficiency increased by omitting attaching the information.

Each of the constituent elements in each of the above-describedembodiments may be configured in the form of an exclusive hardwareproduct, or may be implemented by executing a software program suitablefor the structural element. The constituent elements may be implementedby a program execution unit such as a CPU or a processor which reads andexecutes a software program recorded on a recording medium such as ahard disk or a semiconductor memory. Here, examples of the softwareprogram which implements the moving picture coding apparatus and othersin the above-described embodiments include a program as follows.

The program causes a computer to execute the following moving picturecoding method. The moving picture coding method is a method of merging aprediction direction, a motion vector, and a reference picture index ofat least one merging candidate to code a current block, and the methodincludes: making a determination as to whether or not to code all blocksin a current picture in the skip mode; setting, based on a result of thedetermination, a first flag indicating whether or not a temporallyneighboring block which is included in a picture different from thecurrent picture and temporally neighbors the current block is to bereferenced; setting, based on the result of the determination, a valueof a parameter for determining a total number of merging candidates;setting, based on the result of the determination, a second flag foreach block included in the current picture, the second flag indicatingwhether or not the block is to be coded in the skip mode; determining,based on the first flag and the total number of the merging candidates,the at least one merging candidate from among one or more candidatesincluding a neighboring block which is either a block spatiallyneighboring the current block in a picture including the current blockor a temporally neighboring block included in the picture different fromthe current picture, the determined at least one merging candidate beingat least one candidate usable for the merging; selecting a mergingcandidate to be used for coding of the current block from among thedetermined at least one merging candidate; and coding an index whichindicates the selected merging candidate and attaching the coded indexto a bitstream, according to the total number of the merging candidates.

Here, examples of the software program which implements the movingpicture decoding apparatus and others in the above-described embodimentsinclude a program as follows. The program causes a computer to executethe following moving picture decoding method. The moving picturedecoding method is a method of merging a prediction direction, a motionvector, and a reference picture index of at least one merging candidateto decode a current block, and the method includes: decoding a firstflag indicating whether or not a temporally neighboring block which isincluded in a picture different from the current picture and temporallyneighbors the current block is to be referenced; decoding a value of aparameter for determining a total number of merging candidates; decodinga second flag which is set for each block included in the currentpicture and indicates whether or not the block is to be decoded in theskip mode; determining, based on the first flag and the total number ofthe merging candidates, the at least one merging candidate from amongone or more candidates including a neighboring block which is either ablock spatially neighboring the current block in a picture including thecurrent block and or a temporally neighboring block included in thepicture different from the current picture, the determined at least onemerging candidate being at least one candidate usable for the merging;and decoding, according to the total number of the merging candidates,an index which indicates a merging candidate to be used for decoding ofthe current block, the merging candidate to be used for decoding of thecurrent block being among the at least one determined merging candidate.

Although the moving picture coding apparatus and moving picture decodingapparatus according to one or more aspects of the present disclosurehave been described based on the embodiments, the present invention isnot limited to these embodiments. Those skilled in the art will readilyappreciate that many modifications of the exemplary embodiments orembodiments in which the constituent elements of the exemplaryembodiments are combined are possible without materially departing fromthe novel teachings and advantages described in the present invention.All such modifications and embodiments are also within scopes of one ormore aspects of the present invention.

Embodiment 5

The processing described in each of embodiments can be simplyimplemented in an independent computer system, by recording, in arecording medium, a program for implementing the configurations of themoving picture coding method (image coding method) and the movingpicture decoding method (image decoding method) described in each ofembodiments. The recording media may be any recording media as long asthe program can be recorded, such as a magnetic disk, an optical disk, amagnetic optical disk, an IC card, and a semiconductor memory.

Hereinafter, the applications to the moving picture coding method (imagecoding method) and the moving picture decoding method (image decodingmethod) described in each of embodiments and systems using thereof willbe described. The system has a feature of having an image coding anddecoding apparatus that includes an image coding apparatus using theimage coding method and an image decoding apparatus using the imagedecoding method. Other configurations in the system can be changed asappropriate depending on the cases.

FIG. 20 illustrates an overall configuration of a content providingsystem ex100 for implementing content distribution services. The areafor providing communication services is divided into cells of desiredsize, and base stations ex106, ex107, ex108, ex109, and ex110 which arefixed wireless stations are placed in each of the cells.

The content providing system ex100 is connected to devices, such as acomputer ex111, a personal digital assistant (PDA) ex112, a cameraex113, a cellular phone ex114 and a game machine ex115, via the Internetex101, an Internet service provider ex102, a telephone network ex104, aswell as the base stations ex106 to ex110, respectively.

However, the configuration of the content providing system ex100 is notlimited to the configuration shown in FIG. 20, and a combination inwhich any of the elements are connected is acceptable. In addition, eachdevice may be directly connected to the telephone network ex104, ratherthan via the base stations ex106 to ex110 which are the fixed wirelessstations. Furthermore, the devices may be interconnected to each othervia a short distance wireless communication and others.

The camera ex113, such as a digital video camera, is capable ofcapturing video. A camera ex116, such as a digital camera, is capable ofcapturing both still images and video. Furthermore, the cellular phoneex114 may be the one that meets any of the standards such as GlobalSystem for Mobile Communications (GSM) (registered trademark), CodeDivision Multiple Access (CDMA), Wideband-Code Division Multiple Access(W-CDMA), Long Term Evolution (LTE), and High Speed Packet Access(HSPA). Alternatively, the cellular phone ex114 may be a PersonalHandyphone System (PHS).

In the content providing system ex100, a streaming server ex103 isconnected to the camera ex113 and others via the telephone network ex104and the base station ex109, which enables distribution of images of alive show and others. In such a distribution, a content (for example,video of a music live show) captured by the user using the camera ex113is coded as described above in each of embodiments (i.e., the camerafunctions as the image coding apparatus according to an aspect of thepresent disclosure), and the coded content is transmitted to thestreaming server ex103. On the other hand, the streaming server ex103carries out stream distribution of the transmitted content data to theclients upon their requests. The clients include the computer ex111, thePDA ex112, the camera ex113, the cellular phone ex114, and the gamemachine ex115 that are capable of decoding the above-mentioned codeddata. Each of the devices that have received the distributed datadecodes and reproduces the coded data (i.e., functions as the imagedecoding apparatus according to an aspect of the present disclosure).

The captured data may be coded by the camera ex113 or the streamingserver ex103 that transmits the data, or the coding processes may beshared between the camera ex113 and the streaming server ex103.Similarly, the distributed data may be decoded by the clients or thestreaming server ex103, or the decoding processes may be shared betweenthe clients and the streaming server ex103. Furthermore, the data of thestill images and video captured by not only the camera ex113 but alsothe camera ex116 may be transmitted to the streaming server ex103through the computer ex111. The coding processes may be performed by thecamera ex116, the computer ex111, or the streaming server ex103, orshared among them.

Furthermore, the coding and decoding processes may be performed by anLSI ex500 generally included in each of the computer ex111 and thedevices. The LSI ex500 may be configured of a single chip or a pluralityof chips. Software for encoding and decoding video may be integratedinto some type of a recording medium (such as a CD-ROM, a flexible disk,and a hard disk) that is readable by the computer ex111 and others, andthe coding and decoding processes may be performed using the software.Furthermore, when the cellular phone ex114 is equipped with a camera,the video data obtained by the camera may be transmitted. The video datais data coded by the LSI ex500 included in the cellular phone ex114.

Furthermore, the streaming server ex103 may be composed of servers andcomputers, and may decentralize data and process the decentralized data,record, or distribute data.

As described above, the clients may receive and reproduce the coded datain the content providing system ex100. In other words, the clients canreceive and decode information transmitted by the user, and reproducethe decoded data in real time in the content providing system ex100, sothat the user who does not have any particular right and equipment canimplement personal broadcasting.

Aside from the example of the content providing system ex100, at leastone of the moving picture coding apparatus (image coding apparatus) andthe moving picture decoding apparatus (image decoding apparatus)described in each of embodiments may be implemented in a digitalbroadcasting system ex200 illustrated in FIG. 21. More specifically, abroadcast station ex201 communicates or transmits, via radio waves to abroadcast satellite ex202, multiplexed data obtained by multiplexingaudio data and others onto video data. The video data is data coded bythe moving picture coding method described in each of embodiments (i.e.,data coded by the image coding apparatus according to an aspect of thepresent disclosure). Upon receipt of the multiplexed data, the broadcastsatellite ex202 transmits radio waves for broadcasting. Then, a home-useantenna ex204 with a satellite broadcast reception function receives theradio waves. Next, a device such as a television (receiver) ex300 and aset top box (STB) ex217 decodes the received multiplexed data, andreproduces the decoded data (i.e., functions as the image decodingapparatus according to an aspect of the present disclosure).

Furthermore, a reader/recorder ex218 (i) reads and decodes themultiplexed data recorded on a recording medium ex215, such as a DVD anda BD, or (i) codes video signals in the recording medium ex215, and insome cases, writes data obtained by multiplexing an audio signal on thecoded data. The reader/recorder ex218 can include the moving picturedecoding apparatus or the moving picture coding apparatus as shown ineach of embodiments. In this case, the reproduced video signals aredisplayed on the monitor ex219, and can be reproduced by another deviceor system using the recording medium ex215 on which the multiplexed datais recorded. It is also possible to implement the moving picturedecoding apparatus in the set top box ex217 connected to the cable ex203for a cable television or to the antenna ex204 for satellite and/orterrestrial broadcasting, so as to display the video signals on themonitor ex219 of the television ex300. The moving picture decodingapparatus may be implemented not in the set top box but in thetelevision ex300.

FIG. 22 illustrates the television (receiver) ex300 that uses the movingpicture coding method and the moving picture decoding method describedin each of embodiments. The television ex300 includes: a tuner ex301that obtains or provides multiplexed data obtained by multiplexing audiodata onto video data, through the antenna ex204 or the cable ex203, etc.that receives a broadcast;

a modulation/demodulation unit ex302 that demodulates the receivedmultiplexed data or modulates data into multiplexed data to be suppliedoutside; and a multiplexing/demultiplexing unit ex303 that demultiplexesthe modulated multiplexed data into video data and audio data, ormultiplexes video data and audio data coded by a signal processing unitex306 into data.

The television ex300 further includes: a signal processing unit ex306including an audio signal processing unit ex304 and a video signalprocessing unit ex305 that decode audio data and video data and codeaudio data and video data, respectively (which function as the imagecoding apparatus and the image decoding apparatus according to theaspects of the present disclosure); and an output unit ex309 including aspeaker ex307 that provides the decoded audio signal, and a display unitex308 that displays the decoded video signal, such as a display.Furthermore, the television ex300 includes an interface unit ex317including an operation input unit ex312 that receives an input of a useroperation. Furthermore, the television ex300 includes a control unitex310 that controls overall each constituent element of the televisionex300, and a power supply circuit unit ex311 that supplies power to eachof the elements. Other than the operation input unit ex312, theinterface unit ex317 may include: a bridge ex313 that is connected to anexternal device, such as the reader/recorder ex218; a slot unit ex314for enabling attachment of the recording medium ex216, such as an SDcard; a driver ex315 to be connected to an external recording medium,such as a hard disk; and a modem ex316 to be connected to a telephonenetwork. Here, the recording medium ex216 can electrically recordinformation using a non-volatile/volatile semiconductor memory elementfor storage. The constituent elements of the television ex300 areconnected to each other through a synchronous bus.

First, the configuration in which the television ex300 decodesmultiplexed data obtained from outside through the antenna ex204 andothers and reproduces the decoded data will be described. In thetelevision ex300, upon a user operation through a remote controllerex220 and others, the multiplexing/demultiplexing unit ex303demultiplexes the multiplexed data demodulated by themodulation/demodulation unit ex302, under control of the control unitex310 including a CPU. Furthermore, the audio signal processing unitex304 decodes the demultiplexed audio data, and the video signalprocessing unit ex305 decodes the demultiplexed video data, using thedecoding method described in each of embodiments, in the televisionex300. The output unit ex309 provides the decoded video signal and audiosignal outside, respectively. When the output unit ex309 provides thevideo signal and the audio signal, the signals may be temporarily storedin buffers ex318 and ex319, and others so that the signals arereproduced in synchronization with each other. Furthermore, thetelevision ex300 may read multiplexed data not through a broadcast andothers but from the recording media ex215 and ex216, such as a magneticdisk, an optical disk, and a SD card. Next, a configuration in which thetelevision ex300 codes an audio signal and a video signal, and transmitsthe data outside or writes the data on a recording medium will bedescribed. In the television ex300, upon a user operation through theremote controller ex220 and others, the audio signal processing unitex304 codes an audio signal, and the video signal processing unit ex305codes a video signal, under control of the control unit ex310 using thecoding method described in each of embodiments. Themultiplexing/demultiplexing unit ex303 multiplexes the coded videosignal and audio signal, and provides the resulting signal outside. Whenthe multiplexing/demultiplexing unit ex303 multiplexes the video signaland the audio signal, the signals may be temporarily stored in thebuffers ex320 and ex321, and others so that the signals are reproducedin synchronization with each other. Here, the buffers ex318, ex319,ex320, and ex321 may be plural as illustrated, or at least one buffermay be shared in the television ex300. Furthermore, data may be storedin a buffer so that the system overflow and underflow may be avoidedbetween the modulation/demodulation unit ex302 and themultiplexing/demultiplexing unit ex303, for example.

Furthermore, the television ex300 may include a configuration forreceiving an AV input from a microphone or a camera other than theconfiguration for obtaining audio and video data from a broadcast or arecording medium, and may code the obtained data. Although thetelevision ex300 can code, multiplex, and provide outside data in thedescription, it may be capable of only receiving, decoding, andproviding outside data but not the coding, multiplexing, and providingoutside data.

Furthermore, when the reader/recorder ex218 reads or writes multiplexeddata from or on a recording medium, one of the television ex300 and thereader/recorder ex218 may decode or encode the multiplexed data, and thetelevision ex300 and the reader/recorder ex218 may share the decoding orencoding.

As an example, FIG. 23 illustrates a configuration of an informationreproducing/recording unit ex400 when data is read or written from or onan optical disk. The information reproducing/recording unit ex400includes constituent elements ex401, ex402, ex403, ex404, ex405, ex406,and ex407 to be described hereinafter. The optical head ex401 irradiatesa laser spot in a recording surface of the recording medium ex215 thatis an optical disk to write information, and detects reflected lightfrom the recording surface of the recording medium ex215 to read theinformation. The modulation recording unit ex402 electrically drives asemiconductor laser included in the optical head ex401, and modulatesthe laser light according to recorded data. The reproductiondemodulating unit ex403 amplifies a reproduction signal obtained byelectrically detecting the reflected light from the recording surfaceusing a photo detector included in the optical head ex401, anddemodulates the reproduction signal by separating a signal componentrecorded on the recording medium ex215 to reproduce the necessaryinformation. The buffer ex404 temporarily holds the information to berecorded on the recording medium ex215 and the information reproducedfrom the recording medium ex215. The disk motor ex405 rotates therecording medium ex215. The servo control unit ex406 moves the opticalhead ex401 to a predetermined information track while controlling therotation drive of the disk motor ex405 so as to follow the laser spot.The system control unit ex407 controls overall the informationreproducing/recording unit ex400. The reading and writing processes canbe implemented by the system control unit ex407 using variousinformation stored in the buffer ex404 and generating and adding newinformation as necessary, and by the modulation recording unit ex402,the reproduction demodulating unit ex403, and the servo control unitex406 that record and reproduce information through the optical headex401 while being operated in a coordinated manner. The system controlunit ex407 includes, for example, a microprocessor, and executesprocessing by causing a computer to execute a program for read andwrite.

Although the optical head ex401 irradiates a laser spot in thedescription, it may perform high-density recording using near fieldlight.

FIG. 24 illustrates the recording medium ex215 that is the optical disk.On the recording surface of the recording medium ex215, guide groovesare spirally formed, and an information track ex230 records, in advance,address information indicating an absolute position on the diskaccording to change in a shape of the guide grooves. The addressinformation includes information for determining positions of recordingblocks ex231 that are a unit for recording data. Reproducing theinformation track ex230 and reading the address information in anapparatus that records and reproduces data can lead to determination ofthe positions of the recording blocks. Furthermore, the recording mediumex215 includes a data recording area ex233, an inner circumference areaex232, and an outer circumference area ex234. The data recording areaex233 is an area for use in recording the user data. The innercircumference area ex232 and the outer circumference area ex234 that areinside and outside of the data recording area ex233, respectively arefor specific use except for recording the user data. The informationreproducing/recording unit 400 reads and writes coded audio, coded videodata, or multiplexed data obtained by multiplexing the coded audio andvideo data, from and on the data recording area ex233 of the recordingmedium ex215.

Although an optical disk having a layer, such as a DVD and a BD isdescribed as an example in the description, the optical disk is notlimited to such, and may be an optical disk having a multilayerstructure and capable of being recorded on a part other than thesurface. Furthermore, the optical disk may have a structure formultidimensional recording/reproduction, such as recording ofinformation using light of colors with different wavelengths in the sameportion of the optical disk and for recording information havingdifferent layers from various angles.

Furthermore, a car ex210 having an antenna ex205 can receive data fromthe satellite ex202 and others, and reproduce video on a display devicesuch as a car navigation system ex211 set in the car ex210, in thedigital broadcasting system ex200. Here, a configuration of the carnavigation system ex211 will be a configuration, for example, includinga GPS receiving unit from the configuration illustrated in FIG. 22. Thesame will be true for the configuration of the computer ex111, thecellular phone ex114, and others.

FIG. 25A illustrates the cellular phone ex114 that uses the movingpicture coding method and the moving picture decoding method describedin embodiments. The cellular phone ex114 includes: an antenna ex350 fortransmitting and receiving radio waves through the base station ex110; acamera unit ex365 capable of capturing moving and still images; and adisplay unit ex358 such as a liquid crystal display for displaying thedata such as decoded video captured by the camera unit ex365 or receivedby the antenna ex350. The cellular phone ex114 further includes: a mainbody unit including an operation key unit ex366; an audio output unitex357 such as a speaker for output of audio; an audio input unit ex356such as a microphone for input of audio; a memory unit ex367 for storingcaptured video or still pictures, recorded audio, encoded or decodeddata of the received video, the still pictures, e-mails, or others; anda slot unit ex364 that is an interface unit for a recording medium thatstores data in the same manner as the memory unit ex367.

Next, an example of a configuration of the cellular phone ex114 will bedescribed with reference to FIG. 25B. In the cellular phone ex114, amain control unit ex360 designed to control overall each unit of themain body including the display unit ex358 as well as the operation keyunit ex366 is connected mutually, via a synchronous bus ex370, to apower supply circuit unit ex361, an operation input control unit ex362,a video signal processing unit ex355, a camera interface unit ex363, aliquid crystal display (LCD) control unit ex359, amodulation/demodulation unit ex352, a multiplexing/demultiplexing unitex353, an audio signal processing unit ex354, the slot unit ex364, andthe memory unit ex367.

When a call-end key or a power key is turned ON by a user's operation,the power supply circuit unit ex361 supplies the respective units withpower from a battery pack so as to activate the cell phone ex114.

In the cellular phone ex114, the audio signal processing unit ex354converts the audio signals collected by the audio input unit ex356 invoice conversation mode into digital audio signals under the control ofthe main control unit ex360 including a CPU, ROM, and RAM. Then, themodulation/demodulation unit ex352 performs spread spectrum processingon the digital audio signals, and the transmitting and receiving unitex351 performs digital-to-analog conversion and frequency conversion onthe data, so as to transmit the resulting data via the antenna ex350.Also, in the cellular phone ex114, the transmitting and receiving unitex351 amplifies the data received by the antenna ex350 in voiceconversation mode and performs frequency conversion and theanalog-to-digital conversion on the data. Then, themodulation/demodulation unit ex352 performs inverse spread spectrumprocessing on the data, and the audio signal processing unit ex354converts it into analog audio signals, so as to output them via theaudio output unit ex357.

Furthermore, when an e-mail in data communication mode is transmitted,text data of the e-mail inputted by operating the operation key unitex366 and others of the main body is sent out to the main control unitex360 via the operation input control unit ex362. The main control unitex360 causes the modulation/demodulation unit ex352 to perform spreadspectrum processing on the text data, and the transmitting and receivingunit ex351 performs the digital-to-analog conversion and the frequencyconversion on the resulting data to transmit the data to the basestation ex110 via the antenna ex350. When an e-mail is received,processing that is approximately inverse to the processing fortransmitting an e-mail is performed on the received data, and theresulting data is provided to the display unit ex358.

When video, still images, or video and audio in data communication modeis or are transmitted, the video signal processing unit ex355 compressesand codes video signals supplied from the camera unit ex365 using themoving picture coding method shown in each of embodiments (i.e.,functions as the image coding apparatus according to the aspect of thepresent disclosure), and transmits the coded video data to themultiplexing/demultiplexing unit ex353. In contrast, during when thecamera unit ex365 captures video, still images, and others, the audiosignal processing unit ex354 codes audio signals collected by the audioinput unit ex356, and transmits the coded audio data to themultiplexing/demultiplexing unit ex353.

The multiplexing/demultiplexing unit ex353 multiplexes the coded videodata supplied from the video signal processing unit ex355 and the codedaudio data supplied from the audio signal processing unit ex354, using apredetermined method. Then, the modulation/demodulation unit(modulation/demodulation circuit unit) ex352 performs spread spectrumprocessing on the multiplexed data, and the transmitting and receivingunit ex351 performs digital-to-analog conversion and frequencyconversion on the data so as to transmit the resulting data via theantenna ex350.

When receiving data of a video file which is linked to a Web page andothers in data communication mode or when receiving an e-mail with videoand/or audio attached, in order to decode the multiplexed data receivedvia the antenna ex350, the multiplexing/demultiplexing unit ex353demultiplexes the multiplexed data into a video data bit stream and anaudio data bit stream, and supplies the video signal processing unitex355 with the coded video data and the audio signal processing unitex354 with the coded audio data, through the synchronous bus ex370. Thevideo signal processing unit ex355 decodes the video signal using amoving picture decoding method corresponding to the moving picturecoding method shown in each of embodiments (i.e., functions as the imagedecoding apparatus according to the aspect of the present disclosure),and then the display unit ex358 displays, for instance, the video andstill images included in the video file linked to the Web page via theLCD control unit ex359. Furthermore, the audio signal processing unitex354 decodes the audio signal, and the audio output unit ex357 providesthe audio.

Furthermore, similarly to the television ex300, it is possible for aterminal such as the cellular phone ex114 to have 3 types ofimplementation configurations including not only (i) a transmitting andreceiving terminal including both a coding apparatus and a decodingapparatus, but also (ii) a transmitting terminal including only a codingapparatus and (iii) a receiving terminal including only a decodingapparatus. Although the digital broadcasting system ex200 receives andtransmits the multiplexed data obtained by multiplexing audio data ontovideo data in the description, the multiplexed data may be data obtainedby multiplexing not audio data but character data related to video ontovideo data, and may be not multiplexed data but video data itself.

As such, the moving picture coding method and the moving picturedecoding method in each of embodiments can be used in any of the devicesand systems described. Thus, the advantages described in each ofembodiments can be obtained.

Furthermore, various modifications and revisions can be made in any ofthe embodiments in the present disclosure.

Embodiment 6

Video data can be generated by switching, as necessary, between (i) themoving picture coding method or the moving picture coding apparatusshown in each of embodiments and (ii) a moving picture coding method ora moving picture coding apparatus in conformity with a differentstandard, such as MPEG-2, MPEG-4 AVC, and VC-1.

Here, when a plurality of video data that conforms to the differentstandards is generated and is then decoded, the decoding methods need tobe selected to conform to the different standards. However, since thestandard to which each of the plurality of the video data to be decodedconforms cannot be detected, there is a problem that an appropriatedecoding method cannot be selected.

In order to solve the problem, multiplexed data obtained by multiplexingaudio data and others onto video data has a structure includingidentification information indicating to which standard the video dataconforms. The specific structure of the multiplexed data including thevideo data generated in the moving picture coding method and by themoving picture coding apparatus shown in each of embodiments will behereinafter described. The multiplexed data is a digital stream in theMPEG-2 Transport Stream format.

FIG. 26 illustrates a structure of the multiplexed data. As illustratedin FIG. 26, the multiplexed data can be obtained by multiplexing atleast one of a video stream, an audio stream, a presentation graphicsstream (PG), and an interactive graphics stream. The video streamrepresents primary video and secondary video of a movie, the audiostream (IG) represents a primary audio part and a secondary audio partto be mixed with the primary audio part, and the presentation graphicsstream represents subtitles of the movie. Here, the primary video isnormal video to be displayed on a screen, and the secondary video isvideo to be displayed on a smaller window in the primary video.Furthermore, the interactive graphics stream represents an interactivescreen to be generated by arranging the GUI components on a screen. Thevideo stream is coded in the moving picture coding method or by themoving picture coding apparatus shown in each of embodiments, or in amoving picture coding method or by a moving picture coding apparatus inconformity with a conventional standard, such as MPEG-2, MPEG-4 AVC, andVC-1. The audio stream is coded in accordance with a standard, such asDolby-AC-3, Dolby Digital Plus, MLP, DTS, DTS-HD, and linear PCM.

Each stream included in the multiplexed data is identified by PID. Forexample, 0x1011 is allocated to the video stream to be used for video ofa movie, 0x1100 to 0x111F are allocated to the audio streams, 0x1200 to0x121F are allocated to the presentation graphics streams, 0x1400 to0x141F are allocated to the interactive graphics streams, 0x1B00 to0x1B1F are allocated to the video streams to be used for secondary videoof the movie, and 0x1A00 to 0x1A1F are allocated to the audio streams tobe used for the secondary audio to be mixed with the primary audio.

FIG. 27 schematically illustrates how data is multiplexed. First, avideo stream ex235 composed of video frames and an audio stream ex238composed of audio frames are transformed into a stream of PES packetsex236 and a stream of PES packets ex239, and further into TS packetsex237 and TS packets ex240, respectively. Similarly, data of apresentation graphics stream ex241 and data of an interactive graphicsstream ex244 are transformed into a stream of PES packets ex242 and astream of PES packets ex245, and further into TS packets ex243 and TSpackets ex246, respectively. These TS packets are multiplexed into astream to obtain multiplexed data ex247.

FIG. 28 illustrates how a video stream is stored in a stream of PESpackets in more detail. The first bar in FIG. 28 shows a video framestream in a video stream. The second bar shows the stream of PESpackets. As indicated by arrows denoted as yy1, yy2, yy3, and yy4 inFIG. 28, the video stream is divided into pictures as I pictures, Bpictures, and P pictures each of which is a video presentation unit, andthe pictures are stored in a payload of each of the PES packets. Each ofthe PES packets has a PES header, and the PES header stores aPresentation Time-Stamp (PTS) indicating a display time of the picture,and a Decoding Time-Stamp (DTS) indicating a decoding time of thepicture.

FIG. 29 illustrates a format of TS packets to be finally written on themultiplexed data. Each of the TS packets is a 188-byte fixed lengthpacket including a 4-byte TS header having information, such as a PIDfor identifying a stream and a 184-byte TS payload for storing data. ThePES packets are divided, and stored in the TS payloads, respectively.When a BD ROM is used, each of the TS packets is given a 4-byteTP_Extra_Header, thus resulting in 192-byte source packets. The sourcepackets are written on the multiplexed data. The TP_Extra_Header storesinformation such as an Arrival_Time_Stamp (ATS). The ATS shows atransfer start time at which each of the TS packets is to be transferredto a PID filter. The source packets are arranged in the multiplexed dataas shown at the bottom of FIG. 29. The numbers incrementing from thehead of the multiplexed data are called source packet numbers (SPNs).

Each of the TS packets included in the multiplexed data includes notonly streams of audio, video, subtitles and others, but also a ProgramAssociation Table (PAT), a Program Map Table (PMT), and a Program ClockReference (PCR). The PAT shows what a PID in a PMT used in themultiplexed data indicates, and a PID of the PAT itself is registered aszero. The PMT stores PIDs of the streams of video, audio, subtitles andothers included in the multiplexed data, and attribute information ofthe streams corresponding to the PIDs. The PMT also has variousdescriptors relating to the multiplexed data. The descriptors haveinformation such as copy control information showing whether copying ofthe multiplexed data is permitted or not. The PCR stores STC timeinformation corresponding to an ATS showing when the PCR packet istransferred to a decoder, in order to achieve synchronization between anArrival Time Clock (ATC) that is a time axis of ATSs, and an System TimeClock (STC) that is a time axis of PTSs and DTSs.

FIG. 30 illustrates the data structure of the PMT in detail. A PMTheader is disposed at the top of the PMT. The PMT header describes thelength of data included in the PMT and others. A plurality ofdescriptors relating to the multiplexed data is disposed after the PMTheader. Information such as the copy control information is described inthe descriptors. After the descriptors, a plurality of pieces of streaminformation relating to the streams included in the multiplexed data isdisposed. Each piece of stream information includes stream descriptorseach describing information, such as a stream type for identifying acompression codec of a stream, a stream PID, and stream attributeinformation (such as a frame rate or an aspect ratio). The streamdescriptors are equal in number to the number of streams in themultiplexed data.

When the multiplexed data is recorded on a recording medium and others,it is recorded together with multiplexed data information files.

Each of the multiplexed data information files is management informationof the multiplexed data as shown in FIG. 31. The multiplexed datainformation files are in one to one correspondence with the multiplexeddata, and each of the files includes multiplexed data information,stream attribute information, and an entry map.

As illustrated in FIG. 31, the multiplexed data information includes asystem rate, a reproduction start time, and a reproduction end time. Thesystem rate indicates the maximum transfer rate at which a system targetdecoder to be described later transfers the multiplexed data to a PIDfilter. The intervals of the ATSs included in the multiplexed data areset to not higher than a system rate. The reproduction start timeindicates a PTS in a video frame at the head of the multiplexed data. Aninterval of one frame is added to a PTS in a video frame at the end ofthe multiplexed data, and the PTS is set to the reproduction end time.

As shown in FIG. 32, a piece of attribute information is registered inthe stream attribute information, for each PID of each stream includedin the multiplexed data. Each piece of attribute information hasdifferent information depending on whether the corresponding stream is avideo stream, an audio stream, a presentation graphics stream, or aninteractive graphics stream. Each piece of video stream attributeinformation carries information including what kind of compression codecis used for compressing the video stream, and the resolution, aspectratio and frame rate of the pieces of picture data that is included inthe video stream. Each piece of audio stream attribute informationcarries information including what kind of compression codec is used forcompressing the audio stream, how many channels are included in theaudio stream, which language the audio stream supports, and how high thesampling frequency is. The video stream attribute information and theaudio stream attribute information are used for initialization of adecoder before the player plays back the information.

In the present embodiment, the multiplexed data to be used is of astream type included in the PMT. Furthermore, when the multiplexed datais recorded on a recording medium, the video stream attributeinformation included in the multiplexed data information is used. Morespecifically, the moving picture coding method or the moving picturecoding apparatus described in each of embodiments includes a step or aunit for allocating unique information indicating video data generatedby the moving picture coding method or the moving picture codingapparatus in each of embodiments, to the stream type included in the PMTor the video stream attribute information. With the configuration, thevideo data generated by the moving picture coding method or the movingpicture coding apparatus described in each of embodiments can bedistinguished from video data that conforms to another standard.

Furthermore, FIG. 33 illustrates steps of the moving picture decodingmethod according to the present embodiment. In Step exS100, the streamtype included in the PMT or the video stream attribute informationincluded in the multiplexed data information is obtained from themultiplexed data. Next, in Step exS101, it is determined whether or notthe stream type or the video stream attribute information indicates thatthe multiplexed data is generated by the moving picture coding method orthe moving picture coding apparatus in each of embodiments. When it isdetermined that the stream type or the video stream attributeinformation indicates that the multiplexed data is generated by themoving picture coding method or the moving picture coding apparatus ineach of embodiments, in Step exS102, decoding is performed by the movingpicture decoding method in each of embodiments. Furthermore, when thestream type or the video stream attribute information indicatesconformance to the conventional standards, such as MPEG-2, MPEG-4 AVC,and VC-1, in Step exS103, decoding is performed by a moving picturedecoding method in conformity with the conventional standards.

As such, allocating a new unique value to the stream type or the videostream attribute information enables determination whether or not themoving picture decoding method or the moving picture decoding apparatusthat is described in each of embodiments can perform decoding. Even whenmultiplexed data that conforms to a different standard is input, anappropriate decoding method or apparatus can be selected. Thus, itbecomes possible to decode information without any error. Furthermore,the moving picture coding method or apparatus, or the moving picturedecoding method or apparatus in the present embodiment can be used inthe devices and systems described above.

Embodiment 7

Each of the moving picture coding method, the moving picture codingapparatus, the moving picture decoding method, and the moving picturedecoding apparatus in each of embodiments is typically achieved in theform of an integrated circuit or a Large Scale Integrated (LSI) circuit.As an example of the LSI, FIG. 34 illustrates a configuration of the LSIex500 that is made into one chip. The LSI ex500 includes elements ex501,ex502, ex503, ex504, ex505, ex506, ex507, ex508, and ex509 to bedescribed below, and the elements are connected to each other through abus ex510. The power supply circuit unit ex505 is activated by supplyingeach of the elements with power when the power supply circuit unit ex505is turned on.

For example, when coding is performed, the LSI ex500 receives an AVsignal from a microphone ex117, a camera ex113, and others through an AVIO ex509 under control of a control unit ex501 including a CPU ex502, amemory controller ex503, a stream controller ex504, and a drivingfrequency control unit ex512. The received AV signal is temporarilystored in an external memory ex511, such as an SDRAM. Under control ofthe control unit ex501, the stored data is segmented into data portionsaccording to the processing amount and speed to be transmitted to asignal processing unit ex507. Then, the signal processing unit ex507codes an audio signal and/or a video signal. Here, the coding of thevideo signal is the coding described in each of embodiments.Furthermore, the signal processing unit ex507 sometimes multiplexes thecoded audio data and the coded video data, and a stream IO ex506provides the multiplexed data outside. The provided multiplexed data istransmitted to the base station ex107, or written on the recordingmedium ex215. When data sets are multiplexed, the data should betemporarily stored in the buffer ex508 so that the data sets aresynchronized with each other.

Although the memory ex511 is an element outside the LSI ex500, it may beincluded in the LSI ex500. The buffer ex508 is not limited to onebuffer, but may be composed of buffers. Furthermore, the LSI ex500 maybe made into one chip or a plurality of chips.

Furthermore, although the control unit ex501 includes the CPU ex502, thememory controller ex503, the stream controller ex504, the drivingfrequency control unit ex512, the configuration of the control unitex501 is not limited to such. For example, the signal processing unitex507 may further include a CPU. Inclusion of another CPU in the signalprocessing unit ex507 can improve the processing speed. Furthermore, asanother example, the CPU ex502 may serve as or be a part of the signalprocessing unit ex507, and, for example, may include an audio signalprocessing unit. In such a case, the control unit ex501 includes thesignal processing unit ex507 or the CPU ex502 including a part of thesignal processing unit ex507.

The name used here is LSI, but it may also be called IC, system LSI,super LSI, or ultra LSI depending on the degree of integration.

Moreover, ways to achieve integration are not limited to the LSI, and aspecial circuit or a general purpose processor and so forth can alsoachieve the integration. Field Programmable Gate Array (FPGA) that canbe programmed after manufacturing LSIs or a reconfigurable processorthat allows re-configuration of the connection or configuration of anLSI can be used for the same purpose. Such a programmable logic devicecan typically execute the moving picture coding method and/or the movingpicture decoding method according to any of the above embodiments, byloading or reading from a memory or the like one or more programs thatare included in software or firmware.

In the future, with advancement in semiconductor technology, a brand-newtechnology may replace LSI. The functional blocks can be integratedusing such a technology. The possibility is that the present disclosureis applied to biotechnology.

Embodiment 8

When video data generated in the moving picture coding method or by themoving picture coding apparatus described in each of embodiments isdecoded, it is possible for the processing amount to increase comparedto when video data that conforms to a conventional standard, such asMPEG-2, MPEG-4 AVC, and VC-1 is decoded. the processing amount probablyincreases. Thus, the LSI ex500 needs to be set to a driving frequencyhigher than that of the CPU ex502 to be used when video data inconformity with the conventional standard is decoded. However, when thedriving frequency is set higher, there is a problem that the powerconsumption increases.

In order to solve the problem, the moving picture decoding apparatus,such as the television ex300 and the LSI ex500 is configured todetermine to which standard the video data conforms, and switch betweenthe driving frequencies according to the determined standard. FIG. 35illustrates a configuration ex800 in the present embodiment. A drivingfrequency switching unit ex803 sets a driving frequency to a higherdriving frequency when video data is generated by the moving picturecoding method or the moving picture coding apparatus described in eachof embodiments. Then, the driving frequency switching unit ex803instructs a decoding processing unit ex801 that executes the movingpicture decoding method described in each of embodiments to decode thevideo data. When the video data conforms to the conventional standard,the driving frequency switching unit ex803 sets a driving frequency to alower driving frequency than that of the video data generated by themoving picture coding method or the moving picture coding apparatusdescribed in each of embodiments. Then, the driving frequency switchingunit ex803 instructs the decoding processing unit ex802 that conforms tothe conventional standard to decode the video data.

More specifically, the driving frequency switching unit ex803 includesthe CPU ex502 and the driving frequency control unit ex512 in FIG. 34.Here, each of the decoding processing unit ex801 that executes themoving picture decoding method described in each of embodiments and thedecoding processing unit ex802 that conforms to the conventionalstandard corresponds to the signal processing unit ex507 in FIG. 34. TheCPU ex502 determines to which standard the video data conforms. Then,the driving frequency control unit ex512 determines a driving frequencybased on a signal from the CPU ex502. Furthermore, the signal processingunit ex507 decodes the video data based on the signal from the CPUex502. For example, it is possible that the identification informationdescribed in Embodiment 6 is used for identifying the video data. Theidentification information is not limited to the one described inEmbodiment 6 but may be any information as long as the informationindicates to which standard the video data conforms. For example, whenwhich standard video data conforms to can be determined based on anexternal signal for determining that the video data is used for atelevision or a disk, etc., the determination may be made based on suchan external signal. Furthermore, the CPU ex502 selects a drivingfrequency based on, for example, a look-up table in which the standardsof the video data are associated with the driving frequencies as shownin FIG. 37. The driving frequency can be selected by storing the look-uptable in the buffer ex508 and in an internal memory of an LSI, and withreference to the look-up table by the CPU ex502.

FIG. 36 illustrates steps for executing a method in the presentembodiment. First, in Step exS200, the signal processing unit ex507obtains identification information from the multiplexed data. Next, inStep exS201, the CPU ex502 determines whether or not the video data isgenerated by the coding method and the coding apparatus described ineach of embodiments, based on the identification information. When thevideo data is generated by the moving picture coding method and themoving picture coding apparatus described in each of embodiments, inStep exS202, the CPU ex502 transmits a signal for setting the drivingfrequency to a higher driving frequency to the driving frequency controlunit ex512. Then, the driving frequency control unit ex512 sets thedriving frequency to the higher driving frequency. On the other hand,when the identification information indicates that the video dataconforms to the conventional standard, such as MPEG-2, MPEG-4 AVC, andVC-1, in Step exS203, the CPU ex502 transmits a signal for setting thedriving frequency to a lower driving frequency to the driving frequencycontrol unit ex512. Then, the driving frequency control unit ex512 setsthe driving frequency to the lower driving frequency than that in thecase where the video data is generated by the moving picture codingmethod and the moving picture coding apparatus described in each ofembodiment.

Furthermore, along with the switching of the driving frequencies, thepower conservation effect can be improved by changing the voltage to beapplied to the LSI ex500 or an apparatus including the LSI ex500. Forexample, when the driving frequency is set lower, it is possible thatthe voltage to be applied to the LSI ex500 or the apparatus includingthe LSI ex500 is set to a voltage lower than that in the case where thedriving frequency is set higher.

Furthermore, when the processing amount for decoding is larger, thedriving frequency may be set higher, and when the processing amount fordecoding is smaller, the driving frequency may be set lower as themethod for setting the driving frequency. Thus, the setting method isnot limited to the ones described above. For example, when theprocessing amount for decoding video data in conformity with MPEG-4 AVCis larger than the processing amount for decoding video data generatedby the moving picture coding method and the moving picture codingapparatus described in each of embodiments, it is possible that thedriving frequency is set in reverse order to the setting describedabove.

Furthermore, the method for setting the driving frequency is not limitedto the method for setting the driving frequency lower. For example, whenthe identification information indicates that the video data isgenerated by the moving picture coding method and the moving picturecoding apparatus described in each of embodiments, it is possible thatthe voltage to be applied to the LSI ex500 or the apparatus includingthe LSI ex500 is set higher. When the identification informationindicates that the video data conforms to the conventional standard,such as MPEG-2, MPEG-4 AVC, and VC-1, it is possible that the voltage tobe applied to the LSI ex500 or the apparatus including the LSI ex500 isset lower. As another example, it is possible that, when theidentification information indicates that the video data is generated bythe moving picture coding method and the moving picture coding apparatusdescribed in each of embodiments, the driving of the CPU ex502 is notsuspended, and when the identification information indicates that thevideo data conforms to the conventional standard, such as MPEG-2, MPEG-4AVC, and VC-1, the driving of the CPU ex502 is suspended at a given timebecause the CPU ex502 has extra processing capacity. It is possiblethat, even when the identification information indicates that the videodata is generated by the moving picture coding method and the movingpicture coding apparatus described in each of embodiments, in the casewhere the CPU ex502 has extra processing capacity, the driving of theCPU ex502 is suspended at a given time. In such a case, it is possiblethat the suspending time is set shorter than that in the case where whenthe identification information indicates that the video data conforms tothe conventional standard, such as MPEG-2, MPEG-4 AVC, and VC-1.

Accordingly, the power conservation effect can be improved by switchingbetween the driving frequencies in accordance with the standard to whichthe video data conforms. Furthermore, when the LSI ex500 or theapparatus including the LSI ex500 is driven using a battery, the batterylife can be extended with the power conservation effect.

Embodiment 9

There are cases where a plurality of video data that conforms todifferent standards, is provided to the devices and systems, such as atelevision and a cellular phone. In order to enable decoding theplurality of video data that conforms to the different standards, thesignal processing unit ex507 of the LSI ex500 needs to conform to thedifferent standards. However, the problems of increase in the scale ofthe circuit of the LSI ex500 and increase in the cost arise with theindividual use of the signal processing units ex507 that conform to therespective standards.

In order to solve the problem, what is conceived is a configuration inwhich the decoding processing unit for implementing the moving picturedecoding method described in each of embodiments and the decodingprocessing unit that conforms to the conventional standard, such asMPEG-2, MPEG-4 AVC, and VC-1 are partly shared. Ex900 in FIG. 38A showsan example of the configuration. For example, the moving picturedecoding method described in each of embodiments and the moving picturedecoding method that conforms to MPEG-4 AVC have, partly in common, thedetails of processing, such as entropy coding, inverse quantization,deblocking filtering, and motion compensated prediction. It is possiblefor a decoding processing unit ex902 that conforms to MPEG-4 AVC to beshared by common processing operations, and for a dedicated decodingprocessing unit ex901 to be used for processing which is unique to anaspect of the present invention and does not conform to MPEG-4 AVC. Inparticular, since the aspect of the present invention is characterizedby inverse quantization, it is possible, for example, for the dedicateddecoding processing unit ex901 to be used for inverse quantization, andfor the decoding processing unit to be shared by any or all of the otherprocessing, such as entropy decoding, deblocking filtering, and motioncompensation. The decoding processing unit for implementing the movingpicture decoding method described in each of embodiments may be sharedfor the processing to be shared, and a dedicated decoding processingunit may be used for processing unique to that of MPEG-4 AVC.

Furthermore, ex1000 in FIG. 38B shows another example in that processingis partly shared. This example uses a configuration including adedicated decoding processing unit ex1001 that supports the processingunique to an aspect of the present disclosure, a dedicated decodingprocessing unit ex1002 that supports the processing unique to anotherconventional standard, and a decoding processing unit ex1003 thatsupports processing to be shared between the moving picture decodingmethod according to the aspect of the present disclosure and theconventional moving picture decoding method. Here, the dedicateddecoding processing units ex1001 and ex1002 are not necessarilyspecialized for the processing according to the aspect of the presentdisclosure and the processing of the conventional standard,respectively, and may be the ones capable of implementing generalprocessing. Furthermore, the configuration of the present embodiment canbe implemented by the LSI ex500.

As such, reducing the scale of the circuit of an LSI and reducing thecost are possible by sharing the decoding processing unit for theprocessing to be shared between the moving picture decoding methodaccording to the aspect of the present disclosure and the moving picturedecoding method in conformity with the conventional standard.

It should be noted that the above-described embodiments are provided forillustrative purposes and do not limit the scope of the claimedinvention. Those skilled in the art will readily appreciate that manymodifications of the exemplary embodiments or embodiments in which theconstituent elements of the exemplary embodiments are combined arepossible without materially departing from the novel teachings andadvantages of the subjects recited in the claims attached hereto. Allsuch modifications and embodiments are within the scope of the presentdisclosure.

INDUSTRIAL APPLICABILITY

The moving picture coding methods and moving picture decoding methodsaccording to the present disclosure is applicable to multimedia data ofany type, increasing error resistance in coding and decoding of movingpictures. For example, these methods are useful as moving picture codingmethods and moving picture decoding methods for storage, transmission,and communication of data using mobile phones, DVD systems, personalcomputers, or the like.

1. A moving picture decoding apparatus using a candidate to decode acurrent block, the moving picture decoding apparatus comprising: aprocessor; and a non-transitory computer-readable recording mediumhaving stored thereon executable instructions, which when executed bythe processor, cause the moving picture decoding apparatus to: decodeinformation included in a header of a group of blocks, the informationindicating whether or not each block included in the group of blocks isto be decoded in a skip mode; and select a prediction motion vectorcandidate to be used for decoding of the current block from among atleast one prediction motion vector candidate, wherein when theinformation indicates the skip mode is applied, all the blocks includedin the group of the blocks are to be decoded in the skip mode, and theselected prediction motion vector candidate is a zero vector candidatehaving zero values for all components thereof, and all the blocksincluded in the group of the blocks are decoded using the zero vectorcandidate.